JPWO2007026885A1 - Laser image forming apparatus and color image forming method - Google Patents

Abstract

The laser image forming apparatus has a two-dimensional modulation element for performing image modulation, and has laser light sources of four or more colors having different center wavelengths, and has particularly high light sensitivity green (G), yellow green (Y ) Laser light is emitted at the same time, there is no speckle noise in the wavelength range with high visibility, and the laser output of each color is controlled independently to display a vivid image that could not be expressed on a conventional display be able to. In particular, various video representations are possible by modulating the two-dimensional modulation element and the laser beam output in synchronization.

Description

  The present invention relates to a laser image forming apparatus and a color image forming method for displaying an image by modulating light from a laser light source.

  As an image forming apparatus, a projection display that projects an image on a screen is widely used. In general, a lamp light source is used for a projection display. However, the lamp light source has a problem that it has a short lifetime, low light use efficiency, and a limited color reproduction region.

  In order to solve these problems, attempts have been made to use a laser light source as the light source of the image forming apparatus. A laser light source has a longer life than a lamp and has high directivity, so that it is easy to improve the light utilization efficiency. Further, since the laser light source exhibits monochromaticity, the color display area is large and a vivid image can be displayed.

  A schematic view of the laser image forming apparatus is shown in FIG. Light emitted from the RGB three-color laser light sources 1R, 1G, and 1B is guided to the illumination optical system 2 that illuminates the modulation element 71. The illumination optical system 2 includes speckle removing means 3, an optical integrator 4, and a projection optical system 6, and shapes the light of the laser light source into the same shape as the effective surface of the modulation element 71, and makes the light intensity distribution substantially uniform, The modulation element 71 is illuminated. After the image is modulated by the modulation elements of the respective colors, the light is combined by the dichroic prism 9 and the color image is enlarged and projected onto the screen 10 by the projection optical system 8. The speckle removing means 3 is composed of a rotating lenticular lens or the like, and temporally changes the angle of the laser beam to remove speckle noise due to laser beam interference.

  As described above, in a display using a laser light source (hereinafter referred to as a laser display), speckle noise caused by high laser coherence becomes a problem. Speckle noise is fine granular noise that is captured by the observer's eyes because the scattered light interferes when the laser light is scattered on the screen. The speckle noise is a noise in which grains having a size determined by the F (F number) of the observer's eyes and the wavelength of the laser light source are randomly arranged, which obstructs the observer from capturing the screen image and is serious. Causes image degradation. In particular, speckle noise due to green and yellow-green lasers with high human visibility has the greatest effect on image degradation.

  Up to now, with regard to the reduction of speckle noise, for example, there has been a proposal to reduce speckle noise by deflecting light with a deflector at a frequency higher than the frame frequency in the spatial modulator and irradiating the spatial modulator. (For example, Patent Document 1).

In addition, in a laser image forming apparatus using RGB light emitting elements, there is a proposal to use a single modulation element in a time-division manner using an RGB light emitting element array (for example, Patent Document 2).
Japanese Patent Laid-Open No. 10-293268 Japanese Patent Laid-Open No. 2001-249400

  To date, there have been proposals for reducing speckle noise in laser displays, but there are few proposals for reducing speckle noise in the wavelength range with high visibility, which has the greatest effect on the viewer.

  An object of the present invention is to reduce speckle noise in a wavelength range with high visibility in a laser image forming apparatus using a laser light source, and to provide a vivid image that cannot be expressed by a conventional display.

  In order to solve the above problems, a laser image forming apparatus according to claim 1 of the present invention is a laser image forming apparatus having a laser light source and a two-dimensional modulation element that performs image modulation. It is characterized by having a laser light source.

  The laser image forming apparatus according to claim 2 of the present invention is the laser image forming apparatus according to claim 1, wherein the center wavelength of the laser light source is B of 430 to 475 nm, and G and Y of 480 to 560 nm. And a four-color BGYR laser light source of R which is 610 to 680 nm.

  A laser image forming apparatus according to claim 3 of the present invention is the laser image forming apparatus according to claim 2, wherein at least one of the G and Y laser light sources is a wavelength conversion laser. It is.

  According to a fourth aspect of the present invention, there is provided the laser image forming apparatus according to the third aspect, wherein the difference between the center wavelengths of the G and Y laser light sources is 2 nm or more and 60 nm or less. It is a feature.

  Further, in the laser image forming apparatus according to claim 5 of the present invention, in the laser image forming apparatus according to claim 2, among the four-color BGYR laser light sources, the center wavelengths of G and Y are G: 480 to 520 nm, Y: 520 to 560 nm.

  A laser image forming apparatus according to a sixth aspect of the present invention is the laser image forming apparatus according to the second aspect, wherein a color reproduction range that can be displayed using both the G and Y is both the G and Y. A laser beam is emitted from the laser light source.

  A laser image forming apparatus according to claim 7 of the present invention is the laser image forming apparatus according to claim 1, wherein the input image signal input to the image forming apparatus is controlled to output four or more color signals. The output image control signal is converted into an output image control signal.

  A laser image forming apparatus according to an eighth aspect of the present invention is the laser image forming apparatus according to the first aspect, wherein the modulation of the laser light output from the laser light sources of four or more colors is controlled independently for each color. It is characterized by.

  A laser image forming apparatus according to claim 9 of the present invention is the laser image forming apparatus according to claim 8, wherein each color is selected according to an input image signal input to the image forming apparatus and / or a viewing environment. The output power modulation of the laser light source is controlled independently.

  A laser image forming apparatus according to claim 10 of the present invention is the laser image forming apparatus according to claim 1 or 8, wherein the laser image forming apparatus has one two-dimensional modulation element, and the two The two-dimensional modulation element is time-divided and used for the laser light from each of the four or more color laser light sources.

  A laser image forming apparatus according to an eleventh aspect of the present invention is the laser image forming apparatus according to the tenth aspect, wherein each division time of image modulation of the two-dimensional modulation element is modulated in accordance with an input image signal. It is characterized by.

  A laser image forming apparatus according to a twelfth aspect of the present invention is the laser image forming apparatus according to the tenth aspect, wherein each of the division times of the image modulation of the two-dimensional modulation element is determined by a laser beam emitted from a laser light source. It modulates according to the output of the laser light source monitor to monitor and / or the display mode to set.

  According to a thirteenth aspect of the present invention, in the laser image forming apparatus according to the eighth or tenth aspect, the output image control for controlling the output of each color signal of four or more colors converted from the input image signal. The signal includes at least a modulation signal of a two-dimensional modulation element and a modulation signal of laser light intensity.

  A laser image forming apparatus according to a fourteenth aspect of the present invention is the laser image forming apparatus according to the eighth or tenth aspect, wherein the output image control controls the output of each color signal of four or more colors converted from the input image signal. The signal includes at least a modulation signal of a two-dimensional modulation element and a modulation signal of a laser beam emission time.

  A laser image forming apparatus according to a fifteenth aspect of the present invention is the laser image forming apparatus according to the fourteenth aspect, wherein the laser beam emission time is determined by the image modulation of the two-dimensional modulation element according to the input image signal. Each of the divided times is modulated and synchronized.

  According to a sixteenth aspect of the present invention, there is provided the laser image forming apparatus according to the first aspect, wherein the laser light sources of four or more colors are a plurality of color laser light sources with respect to the two-dimensional modulation element. It has a time for emitting laser light at the same time.

  A laser image forming apparatus according to claim 17 of the present invention is the laser image forming apparatus according to claim 16, wherein each of the laser light sources of the plurality of colors has another laser light source with respect to the two-dimensional modulation element. The emission power modulation during the time of simultaneous emission and the emission power modulation during the time when the laser light source emits only a single color to the two-dimensional modulation element are controlled independently. Is.

  A laser image forming apparatus according to claim 18 of the present invention is characterized in that, in the laser image forming apparatus according to claim 1, the color display range in the chromaticity coordinates is controlled in accordance with the viewing environment. .

  A laser image forming apparatus according to claim 19 of the present invention is the laser image forming apparatus according to claim 18, wherein the color display range is wider than the input image signal reference chromaticity range and the input image signal reference color. It is a range according to the degree or a range according to the color reproducible range.

  A laser image forming apparatus according to claim 20 of the present invention is characterized in that, in the laser image forming apparatus according to claim 9 or 17, the laser cooling temperature is controlled in accordance with the emission power modulation of the laser light source. Is.

  A color image forming method according to claim 21 of the present invention is a color image forming method for forming an image using four or more colors of laser light sources and one or a plurality of two-dimensional modulation elements for performing image modulation. In accordance with an input image signal, the image modulation by the one or more two-dimensional image modulation elements and the laser light output modulation of the laser light sources of four or more colors are synchronized to form an image. To do.

  According to the laser image forming apparatus and the color image forming method of the present invention, in the laser image forming apparatus using the laser light source, there is an effect that an image having no noise and large contrast can be displayed.

  That is, according to the laser image forming apparatus of the present invention, since four color laser light sources having different center wavelengths are used, there is no speckle noise and a vivid image that cannot be expressed by a conventional display is displayed. There is an effect that can.

  Further, according to the laser image forming apparatus of the present invention, the four color laser light sources are set to BGYR, and the difference between the center wavelengths of the G and Y laser light sources is set to 2 nm or more and 60 nm or less. There are effects of reducing speckle noise and displaying an image without color unevenness.

  Further, according to the laser image forming apparatus of the present invention, the color reproduction range that can be displayed using both G and Y emits laser light from both the G and Y laser light sources. There is an effect that speckle noise can be reduced by mixing and displaying laser light source colors having high visibility.

  Further, according to the laser image forming apparatus of the present invention, since the laser light output modulation output from the laser light sources of four or more colors is controlled independently for each color, there is an effect that an image with a large contrast can be displayed. is there.

  Further, according to the laser image forming apparatus of the present invention, each division time of the image modulation of the two-dimensional modulation element is modulated according to the output of the laser monitor and / or the display mode to be set. There is an effect that compensation can be made when the brightness or color changes.

  Further, according to the laser image forming apparatus of the present invention, the laser light emission time is synchronously modulated with the modulation of each division time of the image modulation of the two-dimensional modulation element in accordance with the input image signal. The number of gradations and contrast can be increased, and there is an effect that various video expressions are possible.

  In addition, according to the laser image forming apparatus of the present invention, each of the laser light sources of a plurality of colors has its emission power modulation and two-dimensional modulation during the time when another laser light source emits simultaneously to the two-dimensional modulation element. Since the output power modulation during the time when the laser light source emits only a single color to the element is controlled independently, the color temperature is kept unchanged while keeping the power when emitting in a single color. There is an effect that can be adjusted.

  In addition, according to the laser image forming apparatus of the present invention, the color display range in the chromaticity coordinates is controlled according to the viewing environment, so that it is possible to suppress a decrease in contrast due to a change in the viewing environment.

FIG. 1 is a schematic diagram of a laser image forming apparatus according to Embodiment 1 of the present invention. FIG. 2 is a chromaticity diagram showing the color display range according to the embodiment of the present invention. FIG. 3 is a flowchart showing the image forming method according to the first embodiment of the present invention. FIG. 4 is a flowchart showing an image forming method according to the second embodiment of the present invention. FIG. 5 is a diagram showing the laser beam emission timing of the laser image forming apparatus according to Embodiment 2 of the present invention. FIG. 6 shows the laser image forming apparatus according to Embodiment 2 of the present invention, in which the output power modulation during the time when multiple colors are emitted simultaneously and the output power modulation during the time when only one color is emitted are controlled independently. It is a figure showing the laser beam emission timing in the case. FIG. 7 is a schematic diagram of a laser image forming apparatus according to Embodiment 3 of the present invention. FIG. 8 is a diagram showing G and Y laser beam outputs in the laser image forming apparatus according to Embodiment 3 of the present invention. FIG. 9 is a diagram showing an example in which the laser beam emission time is modulated in the laser image forming apparatus according to Embodiment 3 of the present invention. FIG. 10 is a diagram illustrating laser light emission time control in the laser image forming apparatus of the present invention. FIG. 11 is a chromaticity diagram showing a color display range in the laser image forming apparatus of the present invention. FIG. 12 is a schematic view of a conventional laser image forming apparatus.

(Explanation of symbols)
DESCRIPTION OF SYMBOLS 100, 200 Laser image forming apparatus 101B Blue laser light source 101G Green laser light source 101Y Yellow green laser light source 101R Red laser light source 102 Illumination optical system 103, 1031-1033 Speckle noise removal means 104, 1041-1043 Optical integrator 106, 1061-1063 Projection optical system 107, 1071 to 1073 Two-dimensional modulation element 108 Projection optical system 109 Dichroic prism 10 Screen 121 Dichroic mirror 122 Lens 1061a, 1063a Mirror 1061b, 1062, 1063b Field lens 300 Laser image forming apparatus 1R Red laser light source 1G Green laser light source 1B Blue laser light source 2 Illumination optical system 3 Speckle removal means 4 Optical integrator 6 Projection optical system 61 Mirror 62 Field lens 71 Two-dimensional modulation element 8 Projection optical system 9 Dichroic prism 10 Screen

Embodiments of the present invention will be described below with reference to the drawings.
(Embodiment 1)
FIG. 1 is a schematic diagram of a laser image forming apparatus 100 according to Embodiment 1 of the present invention. FIG. 1 shows a projection display (laser display) using a plurality of laser light sources and a single modulation element.

  In FIG. 1, a laser image forming apparatus 100 according to the first embodiment includes four (4) laser light sources (101B, 101G, 101Y) of blue (B), green (G), yellow-green (Y), and red (R). , 101R), a modulation element 107 that modulates an image, an illumination optical system 102 that illuminates the modulation element 107, and a projection optical system 108 that projects a two-dimensional image on the screen 10. The light emitted from the laser light sources (101B, 101G, 101Y, 101R) of each color is guided to the illumination optical system 102 that illuminates the modulation element 107. The illumination optical system 102 includes speckle noise removing means 103, an optical integrator 104, and a projection optical system 106. The light of the laser light source is shaped into the same shape as the effective surface of the modulation element 107, and the light intensity distribution is made substantially uniform. Then, the modulation element 107 is illuminated. In the first embodiment, one modulation element 107 and one light integrator 104 are used for four colors of light, and after the four colors are combined by the dichroic mirror 121, the combined light is combined with the light integrator 104 and the modulation element. Guided to 107. In order to combine the four colors, the polarization directions of the laser beams can be changed and combined using a polarizing prism or the like. Further, it is only necessary to design the optical path so that the laser beams of the respective colors can enter the optical integrator 104 without being multiplexed.

  The four colors of laser light are sequentially emitted, and one modulation element 107 is time-divided and used, and a color image is displayed by time-average additive color mixing on the screen. The sequential emission of laser light may always be emitted one color at a time, or may be combined with the time during which laser light is emitted simultaneously from a plurality of color laser light sources.

  The modulation element 107 according to Embodiment 1 is a two-dimensional modulation element, and an element having a switching frequency of several hundred Hz or more is used. Specifically, a reflection type two-dimensional modulation element composed of a digital micromirror device (DMD) is used. The two-dimensional image is enlarged and projected on the screen 10 by the projection optical system 108, and the viewer can see a vivid image.

  As described above, in the laser image forming apparatus according to the first embodiment, one modulation element 107 is time-divided and used, but the laser image forming apparatus uses a plurality of modulation elements corresponding to each color. On the other hand, when one modulation element is used in a time-sharing manner with RGYB four-color laser light sources, the laser emission time of each laser light source is short, so that the output peak power of the laser light source is four times necessary to obtain the same white luminance. It becomes. In order to obtain a high emission peak power of a laser light source, it is necessary to increase the number of laser light sources in each color and the emission peak power per laser light source, which causes problems in cost and reliability. In the present invention, it is possible to suppress the emission peak power by having time to emit laser beams simultaneously from the laser light sources of a plurality of colors. For example, while RGYB alone emits to obtain white luminance, peak power for obtaining the same white luminance can be suppressed to 75%, light source cost can be reduced, and reliability can be obtained.

  In the case of using a plurality of colors at the same time, a light source such as a lamp or LED has a problem that although brightness is ensured, color contrast is lowered due to additive color mixing, and sufficient color reproduction cannot be performed. In particular, it becomes impossible to reproduce a color having high brightness near the apex of the RGB triangle in the color reproduction range indicated by the chromaticity coordinates. However, in the present invention, by using a monochromatic laser light source, it is possible to brightly display RGYB colors with high saturation and to secure a sufficient color reproduction range. Since the laser light source is monochromatic, the color purity is extremely high, and it is possible to display a color with higher saturation than conventional displays. When the laser light source is used, the colors in the image signal range and the range that is often seen in daily life are mixed colors of the laser light source colors (inside the RGB triangle). It is possible to reproduce the color sufficiently while using it.

  The laser image forming apparatus of the present invention has a modulation element that performs image modulation, and has laser light sources of four or more colors having different center wavelengths. Speckle noise due to laser light interference causes fine fluctuations in the light intensity distribution to the viewer, but the speckle pattern generated from laser light with different center wavelengths is different, and if the viewer perceives different patterns simultaneously, Fluctuation averaging occurs, and the amount of fluctuation with respect to the total light intensity is reduced. Even if the perception of different patterns is not exactly the same in time, if different patterns reach the viewer within a time period that the viewer cannot distinguish, the patterns are perceived as overlapping, reducing the amount of fluctuation (speckle noise) Will be. A general laser image forming apparatus is composed of three colors of RGB. However, since four colors are used in the present invention, the number of patterns increases and speckle noise is reduced.

  The center wavelength of the laser light source of the present invention is four colors BGYR of blue (B) of 430 to 475 nm, green (G) and yellow green (Y) of 480 to 560 nm, and red (R) of 610 to 680 nm. It is preferable to have at least the laser light source.

  In the laser image forming apparatus according to the first embodiment, it is preferable to have the color display range size and brightness, which are the characteristics of the laser image forming apparatus. For this reason, the center wavelength of the blue (B) laser light is preferably 430 to 475 nm with high visibility and a small CIE chromaticity coordinate y value, and the center wavelength of the red (R) laser light has high visibility and color. 610-680 nm with a large degree coordinate x value is preferable. The central wavelengths of the green (G) laser and the yellow-green (Y) laser light have high visibility, and by increasing any y value and decreasing any x value on the chromaticity coordinates, brightness and color The size of the display range can be obtained. For this reason, it is preferable that the center wavelengths of G and Y are 480 to 560 nm. By using four colors of laser light, the color display range on the chromaticity diagram is expanded from a triangle in the case of three colors to a quadrangle, increasing the degree of color freedom and enabling vivid display.

  In the first embodiment, a semiconductor laser having a central wavelength of 455 nm is used for B, a wavelength conversion laser having a central wavelength of 490 nm is used for G, a wavelength conversion laser having a central wavelength of 540 nm is used for Y, and a semiconductor laser having a central wavelength of 635 nm is used for R. A CIE chromaticity diagram showing the color display range (thick solid line) of the first embodiment at this time is shown in FIG. FIG. 2A also shows an sRGB standard range (thin solid line) that is a displayable range on a conventional CRT for comparison. In Embodiment 1, it can be seen that a very wide range of color reproduction is possible. When displaying a color according to the image signal, it is only necessary to display the color reproduction range of the sRGB standard. In the first embodiment, since the color reproduction range of sRGB is inside the RGYB square or ΔBYR (dashed line) as shown in FIG. 2B, the RGYB four colors or the BYR three colors of the laser light source are always mixed. The color will be displayed. As a result, due to the monochromaticity of the laser and the wide color display range, color reproduction can be achieved even when a mixed color in which a plurality of colors of laser beams are simultaneously emitted is used in combination. In order to secure a sufficient color reproduction range, it is preferable that the time for emitting a plurality of colors simultaneously is not longer than the time for monochromatic emission even when a laser light source is used.

  Further, since the laser light source exhibits monochromaticity, when displaying a single color (the color of the vertex of the RGYB quadrangle), the color saturation is extremely high, and the image observer feels relatively bright. In order to compensate for this, it is necessary to display colors near the vertices of the RGYB square with relatively low brightness. In the first embodiment, by having time to simultaneously emit laser beams of a plurality of colors, the brightness of a single color can be suppressed, and a balanced color display can be achieved.

  Speckle noise is perceived strongly at a wavelength with high visibility because it causes brightness fluctuations in which light intensity fluctuations are perceived. For this reason, it is preferable that the G and Y laser beams have a wavelength range with high visibility of 480 to 560 nm, and the effect of reducing speckle noise is particularly greater than when two colors are used in other wavelength ranges. Further, when the center wavelengths of the G and Y laser beams are two colors outside the range of 480 to 560 nm, the laser beam having a wavelength shorter than 480 nm is perceived as blue, and if the wavelength is longer than 560 nm, the laser beam is yellow. Perceived. Since the two colors at this time have opposite hues, the speckle noise is recognized as color unevenness in addition to brightness fluctuation. For this reason, even if the speckle pattern is different and the brightness fluctuation is reduced, if it is recognized as color unevenness, the noise reduction effect is lost. For this reason, the center wavelengths of G and Y are preferably in the range of 480 to 560 nm.

  In order to obtain an effect of reducing speckle noise, it is preferable that the center wavelength is different by 2 nm or more so that the correlation between the G and Y speckle patterns is eliminated. In addition, if the difference between the center wavelengths of G and Y is large, it is perceived as color unevenness even if the hue is not opposite. If the difference between the center wavelengths is 60 nm or less within the range of 480 to 560 nm, these speckle patterns are in a substantially mixed color state in which grains near the resolution of the human eye are mixed, and thus are not recognized as color unevenness.

  In the image forming apparatus 100 according to the first embodiment, it is preferable that at least one of the G and Y laser light sources is a wavelength conversion laser. The wavelength conversion laser is a laser that performs wavelength conversion of the fundamental laser beam. Wavelength conversion includes a double wave whose wavelength is 1/2, a triple wave whose wavelength is 1/3, and a sum frequency and a difference frequency using two fundamental waves. As the fundamental wave laser beam, a solid laser, a gas laser, a fiber laser, or a semiconductor laser can be used, and the wavelength conversion laser can be designed with a very wide range of wavelengths. For the G and Y laser beams, it is preferable to use a wavelength conversion laser capable of freely selecting a wavelength for the design of color and brightness. In addition, as the laser light sources of other colors, general light sources using laser oscillation can be used, and semiconductor lasers, gas lasers, fiber lasers, solid lasers, and the like can be used.

  Moreover, as for the center wavelength of green (G) and yellowish green (Y), it is preferable that G is 480-520 nm and Y is 520-560 nm. Since the color range perceived by a person is within the horseshoe shape (broken line) indicated by the monochromatic light source spectrum on the chromaticity diagram of FIG. 2A, when four colors are selected, the color becomes a quadrangle that occupies as much of the horseshoe shape as possible. The display range is required. Therefore, by setting the center wavelength of G to 480 to 520 nm and the center wavelength of Y to 520 to 560 nm, it is possible to obtain a wide color display range using the monochromaticity of the laser light and four colors. It can deliver a colorful image that is not available.

  In a laser image forming apparatus using four or more colors of laser light having different wavelengths, an input image signal input to the laser image forming apparatus is converted into an output image control signal for controlling the output of the number of colors of the laser light, and output image control is performed. It is preferable to control each color according to the signal. Specifically, even if the input image signal corresponds to three colors, the input image signal is extended and converted into output image control signals corresponding to four or more color signals. By modulating each color with gradation, the color display range can be expanded and controlled rather than the control with three colors, and a vivid image can be created. In the laser image forming apparatus according to the first embodiment, when converting an input image signal having a high luminance and mixed color into an output image control signal, it is preferable to convert the laser light source color having a high visibility so as to be mixed. . Specifically, in the first embodiment, when displaying White, it is possible to display using only three colors of BGR or BYR, but the display is converted to display using all of BGYR. That is, even when the same color is displayed, the number of speckle patterns generated on the screen can be increased and speckle noise can be reduced by mixing laser light source colors having high visibility. More preferably, when converting into an output image control signal, the laser light source colors having high visibility are set to have the same brightness as much as possible. For example, when displaying White, conversion is performed so that the luminances of G and Y are substantially the same on the screen.

  In the first embodiment, as shown in FIG. 2B, the color within the range of sRGB (thin solid line) is included in ΔBYR (dashed line), and it is within the range of sRGB without outputting G. The color can be displayed. Here, as shown in FIG. 2A, the thick solid line of the square is the color display range of the first embodiment. However, in the present invention, in order to reduce speckle noise, even when only three colors of BYR can be displayed, G is added and the output of the video signal is converted into four colors so that the four colors are displayed. Similarly to this, when display is possible only with three colors of BGR, Y is added to display with four colors. In this way, G is displayed when Y is displayed and Y is displayed simultaneously when G is displayed, so that laser light source colors with high visibility are mixed and displayed, thereby reducing speckle noise. be able to. In this way, it is preferable that the color reproduction range that can be displayed using both G and Y displays both G and Y outputs. In particular, in a bright image (display such as White), it is preferable that the luminance component of each color of the pixel displayed on the screen is converted into a display signal of four colors so that G and Y are substantially the same.

  When G and Y are displayed with substantially the same luminance, the speckle noise reduction effect is greatest. Here, the substantially same luminance is a luminance value of 2/3 to 3/2 for one side. A pixel signal of a bright image is when the luminance value of the input signal is 0.8 times or more that of the input signal that provides the maximum luminance.

  In a laser image forming apparatus using a laser light source, a method of scanning a laser beam pixel by pixel on a screen has been proposed. In the present invention, an image modulated by a two-dimensional or one-dimensional modulation element is projected on a screen. To do. When scanning laser light pixel by pixel, the power density increases because a convergent beam is used, and control becomes very difficult when a high output (bright) image is formed. On the other hand, when a two-dimensional or one-dimensionally spread beam is used on the modulation element, a high-power laser beam can be easily used, and a bright image can be delivered to the viewer. In particular, when a two-dimensional modulation element is used, the power density can be lowered as compared with one dimension, and control becomes easier. As the two-dimensional modulation element, an element using a two-dimensional array micromirror, a two-dimensional array liquid crystal element, or the like can be used.

FIG. 3 is a flowchart showing a color image forming method of the laser image forming apparatus according to the first embodiment.
First, the input image signal is converted into an output image control signal for controlling the output of each color signal of four colors (BGYR). Then, in accordance with the output image control signal, the two-dimensional modulation element is modulated and the modulation of the laser beam emission output is controlled independently for each of the B, G, Y, and R colors. In the laser image forming apparatus according to the first embodiment, one two-dimensional modulation element is used for four-color laser light sources, and the laser light emission timing of each color and the image modulation timing of each color in the two-dimensional modulation element are determined. Control is performed in synchronization, and laser beams of different colors are sequentially emitted from the laser light sources, and the two-dimensional modulation element sequentially modulates the images of the respective colors to form a color image.

  In the laser image forming apparatus of the first embodiment, the emitted light intensity of the laser light is changed independently for each color for each frame by the image signal. The output image can represent a gradation image obtained by multiplying the intensity of the laser beam and the modulation by the modulation element. For example, if the modulation element controls 256 gradations and the laser light intensity is controlled by 16 gradations from the minimum value to the maximum value, one frame can express 256 gradations of 4 colors, and the sequence includes 4 colors 256 × 16 (4096) gradation image representation is possible. If the laser light intensity control width (maximum value / minimum value) is 1000 and the contrast performance of the modulation element is 1000: 1, the contrast of the sequence is 1000000: 1, and rich image expression is possible.

  The laser image forming apparatus of the present invention has a two-dimensional modulation element, and controls the light output modulation of the laser light source independently for each color. By performing image modulation with a two-dimensional modulation element and controlling each color independently, the color expression of the sequence can be enriched as described above, and the laser light emission intensity control width of each color is widened. An image with very high contrast can be obtained. In addition, the light output control of the laser light source can be adjusted according to the viewing environment or the like for color adjustment of the entire image, and the light output gradation can be given by an image signal. In the present invention, laser light output modulation for each color is controlled independently, and image modulation is performed by a two-dimensional modulation element, whereby finer adjustments can be made and an image with a wide contrast can be provided. Since the laser image forming apparatus of the present invention uses a laser light source, high-speed and linear output control can be performed by current-voltage control to the light source, and as a video, high-speed modulation for each frame and a wide dynamic range are possible. Can control.

  Further, in the laser image forming apparatus of the present invention, by controlling the emission power modulation of the laser light source independently for each color, the laser light output of each laser light source can be suppressed and output according to the image, and the light output is related. It is possible to save power. In addition, the laser light source can be used with a long life by suppressing the laser light output. Further, by performing image modulation in synchronization with the modulation element, the number of gradations and contrast of the image can be increased, and various video expressions can be made possible.

  In the first embodiment, it is preferable that the independent control of the laser light source emission power modulation is performed according to the input image signal and / or viewing environment. By modulating the emission power of the laser light source in accordance with the input image signal, the number of gradations and contrast can be increased and power can be saved as described above. Since a laser light source is used in the present invention, high-frequency power modulation is possible, and power modulation can be performed for each frame and within one frame, which was not possible with a lamp type or the like.

  In addition, by changing the emission power independently for each color according to the viewing environment, even if the viewing environment changes, the color change can be compensated for display. In the present invention, in addition to the brightness of a single color, a mixed color at the time of simultaneous emission of a plurality of colors can be controlled, so that even if the viewing environment changes, the color change can be widely compensated. It should be noted that, in the case where the viewing environment is dark or the like, even when the brightness to be displayed is suppressed, it is possible to control the color change compensation while also saving power by suppressing the output power.

  Further, in the first embodiment, each of the four color laser light sources has one optical integrator and a two-dimensional modulation element, and sequentially emits laser light to use the two-dimensional modulation element in a time-sharing manner. Image modulation is performed. When using laser light sources of a plurality of colors, if an optical component and a modulation element are prepared for each color, the size and cost are increased. In the present invention, it is preferable to sequentially emit laser beams to laser light sources of a plurality of colors and use only one optical integrator and a two-dimensional modulation element, respectively. The system can be reduced in size and cost.

  In the laser image forming apparatus of the first embodiment, the output image control signal converted from the input image signal input to the laser image forming apparatus includes a signal for modulating the two-dimensional modulation element of each color, And a signal for modulating the laser light intensity of each color. According to such a configuration, it is possible to perform modulation in which two-dimensional modulation element modulation and laser light intensity modulation are combined, and an output image having rich color expression and large contrast can be obtained.

  The color image forming method of the first embodiment is characterized in that image formation is performed by synchronizing image modulation by a two-dimensional modulation element and four-color laser light output modulation in accordance with an input image signal. . By adopting such a method, it is possible to obtain a color image having a wide color display range, vivid and high contrast.

  The laser image forming apparatus of the present invention preferably includes speckle noise removing means in addition to using a four-color laser light source. By providing the speckle removing means, speckle noise that reaches the viewer can be removed more efficiently. In the first embodiment, an element (specifically, a rotating lenticular lens) that changes the deflection angle of the beam with time is provided. As the speckle noise removing means, means for changing the deflection angle for illuminating the two-dimensional modulation element with time or means for widening the spectrum width and light source area of the laser light may be used.

  As described above, the laser image forming apparatus according to Embodiment 1 of the present invention is a laser image forming apparatus having a laser light source and a two-dimensional modulation element that performs image modulation, in which red (R), green (G), Four color laser light sources (101R, 101G, 101Y, 101B) having different center wavelengths of yellow green (Y) and blue (B) are used, and in particular, lasers of G and Y which are laser light source colors having high visual sensitivity. Since light can be emitted and displayed at the same time, speckle noise in a wavelength region with high visibility can be reduced.

  In addition, since the difference between the central wavelengths of the G and Y laser light sources (101G, 101Y) is set to 2 nm or more and 60 nm or less, speckle noise in a wavelength range with high visibility is reduced and an image without color unevenness is displayed. can do.

  In addition, the color reproduction range that can be displayed using both G and Y reduces speckle noise in a wavelength range with high visibility by displaying both G and Y outputs. be able to.

  Further, since the light output modulation of the laser light source is controlled independently for each color, finer adjustments can be made according to the image, and an image with a wide contrast can be provided.

  In addition, since the image modulation by the single two-dimensional modulation element 107 and the four-color laser light output modulation are synchronized in accordance with the input image signal, the image formation is performed. It can be increased, and various video expressions can be made possible.

(Embodiment 2)
The laser image forming apparatus according to Embodiment 2 of the present invention uses the division time, which is the modulation time for each color of the two-dimensional modulation element, when performing image modulation from each laser light source in the laser image forming apparatus of Embodiment 1. It is to be modulated.

  FIG. 4 is a flowchart of the color image forming method of the laser image forming apparatus according to the second embodiment. Since the configuration of the laser image forming apparatus according to the second embodiment is the same as that of the laser image forming apparatus 100 according to the first embodiment, the description thereof is omitted.

  In the laser image forming apparatus according to Embodiment 2, the division time for the modulation operation of each color of the two-dimensional modulation element is modulated in accordance with an input image signal input to the laser image forming apparatus. Specifically, for example, assuming that 1 frame is 1/60 sec, each division time of blue (B), green (G), yellow green (Y), and red (R) is (B, G , Y, R) (unit: sec) is (1/240, 1/240, 1/240, 1/240), and in another frame B (1/480, 1/480, 1/240, 1 / 120). At the same time, in the laser light output modulation, the laser light emission time is modulated so as to be within each division time of the image modulation of the two-dimensional modulation element, and the laser light intensity is also modulated independently for each color.

  In the laser image forming apparatus according to the second embodiment, it is preferable to modulate the division time of the two-dimensional modulation element into the laser light sources of the respective colors according to the input image signal. By modulating the division time, the number of gradations of each color can be changed for each frame, and only the number of gradations of necessary colors can be increased. For example, in a sunset scene, the red (R) division time can be increased, the number of red gradations can be increased, and the red expression can be made finer.

  The output image control signal converted from the input image signal preferably includes a signal for modulating the laser beam emission time together with a signal for modulating the two-dimensional modulation element, as in the first embodiment. By performing laser beam emission time modulation, laser beam output modulation can be performed even at a constant intensity. More preferably, the laser beam emission time is synchronously modulated with each division time of the image modulation of the two-dimensional modulation element. According to such a configuration, it is possible to use each division time for image modulation of the two-dimensional modulation element without waste.

FIG. 5 shows another example of the laser emission pattern configuration of the laser image forming apparatus according to the second embodiment.
For example, when the input image signal is a dark scene, each color is sequentially emitted as shown in FIG. 5A and a period k in which the output of all colors is lowered is provided. When the input image signal is a bright scene, As shown in FIG. 5B, a plurality of colors (four colors in the figure) are emitted simultaneously, and a period w for emitting a mixed color pattern is provided. During a period in which a mixed color W (White) pattern is emitted, the modulation element also modulates an image according to W. At this time, the input image signal is converted into five colors corresponding to R, G, Y, B, and W to form an image of each color. The display pattern of the period w in which a plurality of colors are emitted converts the signal so as to correspond to the brightness of the pixel.

  In the second embodiment, as in the first embodiment, it is preferable to emit at least two colors G and Y at the same time during a period in which a plurality of colors are emitted. Outputs of two colors G and Y in a multi-color emission period can be reliably applied to a pixel displaying a bright image signal, and a pixel displaying a bright image signal with remarkable speckle noise can be efficiently converted to G. And Y and Y output are combined to reduce speckle noise.

  Further, in the second embodiment, it is preferable that the combination of R and G and Y and B that are close to the opposite hue is emitted continuously, and thereby the color blur due to the sequential emission is reduced. Further, as shown in FIG. 6, it is preferable that G and Y are emitted continuously because a reduction effect of speckle noise is easily obtained. Specifically, it is preferable that R → G → Y → B →... Or B → Y → G → R →... As shown in FIG. Moreover, you may provide the period which cuts off multi-color emission or an output between the said emission orders.

  Further, in the second embodiment, the modulation element and the laser light source perform modulation in synchronization with the mixed color that emits a plurality of colors at the same time. By controlling the output power modulation when the light is emitted simultaneously at the same time, the output power ratio (mixing ratio) simultaneously emitted can be controlled while performing monochromatic power modulation. it can.

  FIG. 6 is a diagram showing the laser beam emission timing in the case where the emission power modulation during the time when a plurality of colors are emitted simultaneously and the emission power modulation when only a single color is emitted are controlled independently. In this example, the temperature is adjusted by White that emits four colors simultaneously.

  In FIG. 6, an image in which the ratio of Red is reduced and the color temperature is increased is shown. In the present invention, by changing the mixing ratio of the power for emitting a plurality of colors at the same time, it is possible to cope with changes such as the color temperature depending on the viewing environment and the viewer's preference. In the example of FIG. 6, the color temperature can be adjusted while changing the output power ratio of the four colors at the same time, while maintaining the power when the RGYB single color is emitted. In the second embodiment, the example in which the emission power ratio is changed when displaying White has been described. Similarly, when a plurality of colors other than White are emitted, power mixing is performed depending on the viewing environment and the preference of the viewer. The ratio can be controlled.

  As described above, the laser image forming apparatus according to the second embodiment of the present invention is a laser image forming apparatus having one optical integrator and a two-dimensional modulation element. Thus, it is used for a laser light source of a plurality of colors, and each division time of the time-division two-dimensional modulation element is modulated in accordance with the input image signal. The number can be changed and only the number of gradations of necessary colors can be expanded.

  In addition, pixels that display bright image signals such as White are displayed using four-color laser light sources including G and Y, so that pixels that display bright image signals with remarkable speckle noise are efficiently displayed. It is possible to reduce the speckle noise by using a combination of G and Y.

  In addition, since the output power modulation during the time when multiple colors are emitted simultaneously and the output power modulation during the time when only a single color is emitted are controlled independently, it is the same when emitting in a single color. The color temperature can be adjusted.

(Embodiment 3)
The laser image forming apparatus according to Embodiment 3 of the present invention uses four color laser light sources in a laser image forming apparatus that uses three optical integrators and two-dimensional modulation elements.

  FIG. 7 is a schematic diagram of a laser image forming apparatus 200 according to Embodiment 3 of the present invention. In FIG. 7, the same components as those in FIG.

  The laser image forming apparatus 200 according to Embodiment 3 includes three optical integrators 1041 to 1043, two-dimensional modulation elements 1071 to 1073, and four color laser light sources (101R, 101G, 101Y, and 101B). In the third embodiment, the green laser light source 101G and the yellow-green laser light source 101Y form a set and share one set of the optical integrator 1042 and the two-dimensional modulation element 1072. The two-dimensional image modulation elements 1071 to 1073 are transmissive two-dimensional modulation elements, and specifically have a configuration in which a liquid crystal element array and a polarizer are combined. Blue (B) and red (R) each have a pair of light integrators 1041 and 1043 and two-dimensional modulation elements 1071 and 1073, and the four colors of laser light are integrated and additively mixed on the screen, Vivid images can be seen.

  The illumination optical system 102 includes speckle removing means 1031 to 1033, optical integrators 1041 to 1043, and projection optical systems 1061 to 1063, and shapes and uniforms the light of the laser light source to illuminate the two-dimensional modulation elements 1071 to 1073. In the third embodiment, the light from the three two-dimensional modulation elements 1071 to 1073 is combined by the dichroic prism 109, and the combined light causes the projection optical system 108 to enlarge and project a color image on the screen 10.

  In the third embodiment, a semiconductor laser with a central wavelength of 455 nm is used as 101B, a wavelength conversion laser with a central wavelength of 515 nm is used as 101G, a wavelength conversion laser with 532 nm is used as 101Y, and a semiconductor laser with a central wavelength of 635 nm is used as 101R. The color display range of the third embodiment is shown in FIG. In the third embodiment, like the color display range of the first embodiment (thick solid line shown in FIG. 2 (a)), a range (two-dot chain line) that is much wider than the sRGB standard range (thin solid line). Color display is possible. Similarly to the first embodiment, speckle noise can be reduced by superimposing the G and Y laser light primaries.

  In the third embodiment, the green (G) and yellow-green (Y) image modulations share the two-dimensional modulation element 1072, for example, the following first and second modulations a) and b). Use the method. The input image signal input to the laser image forming apparatus is converted into an output image control signal for controlling the output of each of the four color signals, as in the first embodiment.

  a) First modulation method

  The image modulation pattern of the two-dimensional modulation element is the same pattern for G and Y, and one image modulation pattern is given to the total laser light output of G and Y.

  FIG. 8 shows an example of G and Y laser beam outputs. In FIG. 8, during the period of one image modulation pattern, the total light of G and Y illuminates the modulation element.

  First, FIG. 8A is a diagram showing an example of controlling the output and ratio of G and Y that illuminate one image modulation pattern by the ratio of the laser emission power. In the example of FIG. 8 (a), the G and Y laser emission power ratio and output change for each image modulation pattern, and the output and color for illuminating the modulation element change according to the image signal, display mode, etc. This is a preferable modulation method that enables a wide range of color display, high contrast, and multiple gradations. For bright image signals, the outputs of G and Y are given high, and the modulation element is illuminated so that the luminances of G and Y are substantially the same. By using such a modulation method, the luminance ratio of G and Y to be displayed can be made substantially the same for bright pixels to be displayed, and speckle noise can be reduced.

  FIG. 8B is a diagram showing an example in which the output and ratio of G and Y that illuminate one image modulation pattern are controlled by the pulse time width of laser light emission. In the example of FIG. 8B, in the case of a bright image signal, in order to increase the average output in one image modulation pattern, the emission time ratio of G and Y in one image modulation pattern is increased, and one image of G and Y is increased. The laser beam emission power is controlled so that the luminance in the modulation pattern is substantially the same.

  As described above, the first modulation method shown in FIGS. 8A and 8B illuminates one image modulation pattern of the image modulation element with the total output light of G and Y. This is a preferable modulation method capable of displaying with a preferable luminance ratio of G and Y.

  The output image control signals for G and Y include the modulation signal of the same two-dimensional modulation element and the respective laser beam output signals.

  8A and 8B show an example in which the output and ratio of G and Y are changed for each pattern of the modulation element by an input image signal or the like. The output and ratio of Y and Y may be changed, or the output and ratio of G and Y may always be constant. When the output and ratio of G and Y are constant, the G and Y laser light output signals may be the same.

  b) Second modulation method

  The image modulation of the two-dimensional modulation element is time-divided by G and Y as in the first and second embodiments, and two colors are modulated. The G and Y output image control signals include the modulation signals of the respective two-dimensional modulation elements and the laser light output modulation signals, and are synchronized with the timing of image modulation time-divided in the two-dimensional modulation elements. Laser beam is emitted. Laser light output modulation may modulate either the laser light intensity or the emission time, or both. When modulating the laser emission time, each division time of image modulation of the two-dimensional modulation element may be synchronized and modulated. Thereby, a wide range of color display is possible even within a frame, and a more preferable modulation method can be obtained.

  FIG. 9 is a diagram showing an example when the laser beam emission time is modulated while the division timing of the two-dimensional modulation element is kept the same. When the image modulation pattern of the two-dimensional image modulation element is a G-compatible pattern, Y laser light is emitted to illuminate the two-dimensional modulation element. Similarly, when the image modulation pattern is a Y-corresponding pattern, G laser light is emitted to illuminate the two-dimensional modulation element. The example of FIG. 9 is a preferable modulation method that can output G and Y laser beams simultaneously to pixels to be displayed by adding Y and G outputs in the case of either G or Y modulation patterns. Further, in the second modulation method, the laser light output is controlled by changing the emission time of the laser light applied in the modulation pattern of either G or Y according to the input image signal. At this time, in a bright scene, by adding more laser light output, it is possible to compensate for the brightness displayed on the screen to be the maximum brightness, and it is possible to always add G + Y laser light output to bright pixels. Noise can be reduced.

  In the second modulation method, the laser light output applied to any one of the G and Y patterns is changed depending on the input image signal and the display mode, but the laser light output applied to each of these patterns is constant. Also good.

  In the laser image forming apparatus according to the third embodiment, green (G) and yellow green (Y) share the two-dimensional modulation element 1072, but red (R) and blue (B). Controls the modulation of the two-dimensional modulation element and the laser light output modulation independently for each color.

  Similarly to the color image forming method of the first embodiment, the image modulation by the three two-dimensional modulation elements and the four-color laser light output modulation may be synchronized in accordance with the input image signal to perform image formation. Good. By adopting such a method, a color image having a wide color display range, a vivid color and a large contrast can be obtained as in the first embodiment.

  As described above, in the laser image forming apparatus according to Embodiment 3 of the present invention, each of the G and Y laser light sources is shared by using one optical integrator 1042 and two-dimensional modulation element 1072, respectively. Even in a configuration having two modulation elements 1071 to 1073 and optical integrators 1041 to 1043, it becomes possible to use four colors of laser light, and speckle noise with high visibility can be reduced, and the color display range can be reduced. Large and profound visual expression.

(Embodiment 4)
In the laser image forming apparatus according to the fourth embodiment of the present invention, in the laser image forming apparatus according to the second embodiment, the output of the laser light source monitor and / or the display mode is used in order to compensate for changes in image brightness and color. Accordingly, the laser beam emission time and the image modulation division time of the two-dimensional modulation element are controlled.

  FIG. 10A shows an example in which the emission time is controlled in accordance with a signal from the light source monitor of the Red laser light source 101R. The laser light source monitor monitors the laser light output and the emission wavelength. The Red laser light source 101R of the laser image forming apparatus is provided with a power and wavelength monitor (not shown) using a diffraction grating and a two-divided photodetector. In FIG. 10A, it is monitored by the laser light source monitor that the wavelength of the Red laser light source 101R has shifted to the long wavelength side due to a temperature change, and in accordance with this, the emission time is controlled for the initial setting, and the color of the image Compensates for changes in brightness. The change in the visibility and chromaticity coordinates due to the shift of the emission wavelength of the Red laser light source 101R to a long wavelength is compensated by controlling the emission time of R single color and the simultaneous emission time of plural colors. Note that each division time of the image modulation of the two-dimensional modulation element may be modulated so as to be synchronized with the laser light output after the emission time control according to the laser light source monitor.

  FIG. 10B shows an example of the emission time control when the display mode is set so that white luminance is given priority. Depending on the set display mode, it is possible to display white brightness brightly even if the time for simultaneously emitting a plurality of colors is increased and the peak power of the same laser light source is used. In the example of FIG. 10B, the white luminance can be displayed 10% brighter than the initial brightness. Similarly to the control of FIG. 10B, by increasing the simultaneous emission time of a plurality of colors, even with the same white luminance, the peak power of the laser light source is suppressed, and the lifetime reliability of the laser light source is prioritized. Can also be selected. Each division time of the image modulation of the two-dimensional modulation element may be modulated so as to be synchronized with the laser light output after the emission time control according to the display mode to be set.

  Further, when the laser light source monitor detects that the power of any one of the laser light sources of each color is deteriorated, the brightness and color can be compensated by controlling the emission time in the same manner as described above. Similarly, when the power deterioration of the laser light sources of all colors is detected by the laser light source monitor, the brightness can be compensated by increasing the time width for simultaneous emission.

  As described above, in the laser image forming apparatus according to Embodiment 4 of the present invention, the laser light source sequentially emits monochromatic and plural colors according to the laser light source monitor and / or display mode, and two-dimensional modulation. By controlling each division time of the image modulation of the element, it is possible to adjust the brightness and color of the image, and to compensate when the brightness and color of the image change.

  In the present invention, not only a single RGYB color but also a mixed color in which a plurality of colors are emitted simultaneously can be adjusted to make finer adjustments.

  In the fourth embodiment, power and wavelength are detected by a laser light source monitor, and compensation when the wavelength is changed can be adjusted without forcibly increasing the laser output.

  In addition, by controlling the emission time of sequential emission, a viewer can provide an image with favorable image quality.

(Embodiment 5)
In the laser image forming apparatus according to Embodiment 5 of the present invention, in the laser image forming apparatuses of Embodiments 1 to 4, in order to prevent a decrease in color saturation due to a change in viewing environment, a color is changed according to the viewing environment. The display range is controlled.

  A color adjustment method according to the viewing environment of a laser image forming apparatus having RGYB four-color laser light sources and modulation elements will be described using the laser image forming apparatus 100 of the first embodiment. The laser image forming apparatus 100 can display the color inside the RGYB square (thick solid line) as shown in the color displayable range of the CIExy chromaticity diagram of FIG.

  When the sRGB standard input image signal is normally displayed, color display is performed according to the sRGB standard chromaticity. FIG. 11 shows an example of color display at this time.

  In FIG. 11, in the case of sRGB compliant display (thin solid line), display is performed in a range that includes the sRGB color reproduction range (thin broken line) in accordance with the sRGB reference chromaticity and in which the hue and the like do not deviate from the input signal. . In the case of sRGB compliant display, the color saturation may be displayed higher than that of the conventional display within a range in which the hue does not deviate so as to make use of the laser color display possible range.

  The laser image forming apparatus according to the fifth embodiment is characterized in that the color display range in the chromaticity coordinates is controlled according to the viewing environment. That is, when the viewing environment changes and becomes brighter than the normal display, the viewer sees the illumination light. Therefore, when the same image is displayed as before, the color saturation appears to be lowered. In the fifth embodiment, when the viewing environment becomes bright, the color display range is controlled to be larger than normal. That is, when the color saturation appears to be lowered due to illumination light or the like, as shown in FIG. 11, the color display range is set to a range according to the displayable range (thick broken line). For example, when displaying an input image signal of the sRGB standard, the display can be controlled from the sRGB compliant display to the viewing environment compatible display according to the viewing environment. With this control, even when the viewing environment changes and bright illumination light is in the viewer's eyes, a highly saturated color can be displayed. Since the laser image forming apparatus of the present invention has the monochromaticity of the laser light source, it can display a highly saturated color. Even for the same input image signal, a reduction in color contrast can be compensated by displaying a highly saturated color utilizing monochromaticity.

  Note that the change in chromaticity of an image to be displayed can be processed when the input image signal is converted into an output image control signal for controlling the modulation element and the laser light source power. Changes in the viewing environment may be controlled by a viewing environment monitor (not shown) provided on the display surface of the laser image forming apparatus and the like, or may be set by the viewer as needed.

  Further, the laser image forming apparatus of the present invention is preferably accompanied by power control of the laser light source with respect to a change in the color display range depending on the viewing environment. For example, when the illumination light is very bright, it is possible to further suppress a decrease in color contrast by increasing the power of the laser light source more than usual. Even if the illumination light is not white light but colored illumination, the laser image forming apparatus of the present invention has an independent laser light source of RGYB. A decrease in color contrast can be suppressed. When the viewing environment becomes dark, the power of the laser light source can be suppressed, and the power can be saved while keeping the color perceived by the viewer constant.

  As described above, the laser image forming apparatus according to the fifth embodiment of the present invention is sRGB compliant with the normal display in the color display range when the viewing environment changes and becomes brighter and the color saturation appears to decrease. By controlling the display to display corresponding to the viewing environment, it is possible to prevent a decrease in color saturation due to a change in the viewing environment.

  Although the laser image forming apparatus 100 according to the first embodiment has been described as an example in the fifth embodiment, the color display range is similarly controlled in the laser image forming apparatus 200 according to the third embodiment according to the viewing environment. Needless to say, you can.

  In the laser image forming apparatuses according to Embodiments 1 to 5 of the present invention, it is preferable to simultaneously control the laser cooling temperature when the emission power of the laser light source is modulated by the input image signal or the viewing environment. In particular, when the laser light source power is continuously emitted at a high power, the cooling temperature is controlled to be lowered. By controlling the cooling temperature in accordance with the emission power modulation control of the laser light source, high reliability of the laser light source can be ensured and laser light can be output with high efficiency. Further, in the case of image display in which the laser light source output is suppressed, the cooling power can be suppressed by further increasing the cooling temperature than usual, and further power saving can be performed.

  Further, as the laser light source in the laser image forming apparatuses according to Embodiments 1 to 5 of the present invention, a laser light source such as a semiconductor laser, a wavelength conversion laser, a solid laser, or a gas laser can be used. Moreover, you may comprise the laser light source of 1 color from several lasers.

  In addition, since the laser image forming apparatuses according to Embodiments 1 to 5 of the present invention utilize the monochromaticity of the laser light source, for example, including a case where a single color laser light source is composed of a plurality of lasers of the same color, It is preferable to have monochromaticity. Including the case where the laser light source of the same color is composed of a plurality of lasers, the full width at half maximum of each color of the RGYB four-color laser light source is preferably less than 10 nm. By setting the full width at half maximum to less than 10 nm, the advantage of monochromaticity (narrow spectrum width) can be fully utilized with respect to a conventional light source, and it can be used in the laser image forming apparatus of the present invention. More preferably, the full width at half maximum of the spectrum of the RGYB four-color laser light source is less than 5 nm. If it is less than 5 nm, chromaticity management of each color can be performed more easily.

  In addition, the projection optical system and the screen for projecting the image of the modulation element in the laser image forming apparatuses according to Embodiments 1 to 5 of the present invention are not particularly limited to the embodiment, so long as the viewer can observe the modulation element image. good. The screen may be a reflection type, a front projection type, or a transmission type, a rear projection type. Further, it may be in the form of a liquid crystal display without a projection optical system and having a modulation element as a display surface.

  In the laser image forming apparatuses according to Embodiments 1 to 5 of the present invention, four color laser light sources having different center wavelengths are used. However, the present invention is not particularly limited to this, and five or more colors can be used. .

  Further, in the laser image forming apparatuses according to Embodiments 1 to 5 of the present invention, the four-color laser light sources having different center wavelengths are used, but the two-dimensional spatial modulation elements and / or the respective elements in Embodiments 1 and 2 are used. The modulation control of the laser light source and the fourth and fifth embodiments can be applied to a laser image forming apparatus using three color laser light sources.

  The laser image forming apparatus and the color image forming method of the present invention can be used as an image forming apparatus and method for moving images and still images.

[0002]
Particles of a size determined by the F (F number) and the wavelength of the laser light source are randomly arranged noise, which obstructs the viewer from capturing the screen image and causes serious image degradation. In particular, speckle noise due to green and yellow-green lasers with high human visibility has the greatest effect on image degradation.
[0006]
Up to now, with regard to the reduction of speckle noise, for example, there has been a proposal to reduce speckle noise by deflecting light with a deflector at a frequency higher than the frame frequency in the spatial modulator and irradiating the spatial modulator. (For example, Patent Document 1).
[0007]
In addition, in a laser image forming apparatus using RGB light emitting elements, there is a proposal to use a single modulation element in a time-division manner using an RGB light emitting element array (for example, Patent Document 2).
Patent Document 1: Japanese Patent Laid-Open No. 10-293268 Patent Document 2: Japanese Patent Laid-Open No. 2001-249400 Disclosure of the Invention [0008]
To date, there have been proposals for reducing speckle noise in laser displays, but there are few proposals for reducing speckle noise in the wavelength range with high visibility, which has the greatest effect on the viewer.
[0009]
An object of the present invention is to reduce speckle noise in a wavelength range with high visibility in a laser image forming apparatus using a laser light source, and to provide a vivid image that cannot be expressed by a conventional display.
Means for Solving the Problems [0010]
In order to solve the above problems, a laser image forming apparatus according to claim 1 of the present invention is a laser image forming apparatus having a laser light source and a two-dimensional modulation element for performing image modulation, wherein the center wavelength is 430 to 475 nm. B, G and Y of 480 to 560 nm, and R of 610 to 680 nm, a four-color BGYR laser light source, and at least one of the G and Y laser light sources is a wavelength conversion laser, The difference between the center wavelengths of the G and Y laser light sources is 2 nm or more and 60 nm or less.
[0011]
[0012]

[0003]
[0013]
[0014]
Further, in the laser image forming apparatus according to claim 5 of the present invention, in the laser image forming apparatus according to claim 1, among the four-color BGYR laser light sources, the center wavelengths of G and Y are G: 480 to 520 nm Y: 520 to 560 nm.
[0015]
A laser image forming apparatus according to claim 6 of the present invention is a laser image forming apparatus having a laser light source and a two-dimensional modulation element that performs image modulation. B, 480 to 480 having a center wavelength of 430 to 475 nm. When a pixel having a color gamut that can be displayed by using both G and Y is displayed, a G and Y laser beam source of G and Y of 560 nm and R of 610 to 680 nm is displayed. And Y output from the laser light sources.
A laser image forming apparatus according to a twenty-second aspect of the present invention is the laser image forming apparatus according to the sixth aspect, wherein when displaying pixels of a color gamut that can be displayed using both G and Y, the pixels In this case, the luminance displayed for G and Y is a luminance value of 2/3 to 3/2 with respect to one.
[0016]
A laser image forming apparatus according to claim 7 of the present invention is the laser image forming apparatus according to claim 1, wherein the input image signal input to the image forming apparatus is controlled to output four or more color signals. The output image control signal is converted into an output image control signal.
[0017]
A laser image forming apparatus according to an eighth aspect of the present invention is the laser image forming apparatus according to the first aspect, wherein the modulation of the laser light output from the laser light sources of four or more colors is controlled independently for each color. It is characterized by.
[0018]
A laser image forming apparatus according to claim 9 of the present invention is the laser image forming apparatus according to claim 8, wherein each color is selected according to an input image signal input to the image forming apparatus and / or a viewing environment. The output power modulation of the laser light source is controlled independently.
[0019]
A laser image forming apparatus according to claim 10 of the present invention is the laser image forming apparatus according to claim 1 or 8, wherein the laser image forming apparatus has one two-dimensional modulation element, and the two The two-dimensional modulation element is time-divided and used for the laser light from each of the four or more color laser light sources.
[0020]
A laser image forming apparatus according to an eleventh aspect of the present invention is the laser according to the tenth aspect.

[0004]
In the image forming apparatus, each division time of the image modulation of the two-dimensional modulation element is modulated according to an input image signal.
[0021]
A laser image forming apparatus according to a twelfth aspect of the present invention is the laser image forming apparatus according to the tenth aspect, wherein each of the division times of the image modulation of the two-dimensional modulation element is determined using laser light emitted from a laser light source. It modulates according to the output of the laser light source monitor to monitor and / or the display mode to set.
[0022]
According to a thirteenth aspect of the present invention, in the laser image forming apparatus according to the eighth or tenth aspect, the output image control for controlling the output of each color signal of four or more colors converted from the input image signal. The signal includes at least a modulation signal of a two-dimensional modulation element and a modulation signal of laser light intensity.
[0023]
A laser image forming apparatus according to a fourteenth aspect of the present invention is the laser image forming apparatus according to the eighth or tenth aspect, wherein the output image control controls the output of each color signal of four or more colors converted from the input image signal. The signal includes at least a modulation signal of a two-dimensional modulation element and a modulation signal of a laser beam emission time.
[0024]
A laser image forming apparatus according to a fifteenth aspect of the present invention is the laser image forming apparatus according to the fourteenth aspect, wherein the laser beam emission time is determined by the image modulation of the two-dimensional modulation element according to the input image signal. Each of the divided times is modulated and synchronized.
[0025]
A laser image forming apparatus according to claim 16 of the present invention is a laser image forming apparatus having a laser light source and a two-dimensional modulation element that performs image modulation, and has laser light sources of four or more colors having different center wavelengths. The laser light sources of four or more colors have a time for the laser light sources of a plurality of colors to emit laser light simultaneously to the two-dimensional modulation element.
[0026]
A laser image forming apparatus according to claim 17 of the present invention is the laser image forming apparatus according to claim 16, wherein each of the laser light sources of the plurality of colors has another laser light source with respect to the two-dimensional modulation element. The emission power modulation during the time of simultaneous emission and the emission power modulation during the time when the laser light source emits only a single color to the two-dimensional modulation element are controlled independently. Is.
[0027]
A laser image forming apparatus according to claim 18 of the present invention provides the laser image according to claim 1.

  The present invention relates to a laser image forming apparatus and a color image forming method for displaying an image by modulating light from a laser light source.

  As an image forming apparatus, a projection display that projects an image on a screen is widely used. In general, a lamp light source is used for a projection display. However, the lamp light source has a problem that it has a short lifetime, low light use efficiency, and a limited color reproduction region.

  In order to solve these problems, attempts have been made to use a laser light source as the light source of the image forming apparatus. A laser light source has a longer life than a lamp and has high directivity, so that it is easy to improve the light utilization efficiency. Further, since the laser light source exhibits monochromaticity, the color display area is large and a vivid image can be displayed.

  A schematic view of the laser image forming apparatus is shown in FIG. Light emitted from the RGB three-color laser light sources 1R, 1G, and 1B is guided to the illumination optical system 2 that illuminates the modulation element 71. The illumination optical system 2 includes speckle removing means 3, an optical integrator 4, and a projection optical system 6, and shapes the light of the laser light source into the same shape as the effective surface of the modulation element 71, and makes the light intensity distribution substantially uniform, The modulation element 71 is illuminated. After the image is modulated by the modulation elements of the respective colors, the light is combined by the dichroic prism 9 and the color image is enlarged and projected onto the screen 10 by the projection optical system 8. The speckle removing means 3 is composed of a rotating lenticular lens or the like, and temporally changes the angle of the laser beam to remove speckle noise due to laser beam interference.

  As described above, in a display using a laser light source (hereinafter referred to as a laser display), speckle noise caused by high laser coherence becomes a problem. Speckle noise is fine granular noise that is captured by the observer's eyes because the scattered light interferes when the laser light is scattered on the screen. The speckle noise is a noise in which grains having a size determined by the F (F number) of the observer's eyes and the wavelength of the laser light source are randomly arranged, which obstructs the observer from capturing the screen image and is serious. Causes image degradation. In particular, speckle noise due to green and yellow-green lasers with high human visibility has the greatest effect on image degradation.

  Up to now, with regard to the reduction of speckle noise, for example, there has been a proposal to reduce speckle noise by deflecting light with a deflector at a frequency higher than the frame frequency in the spatial modulator and irradiating the spatial modulator. (For example, Patent Document 1).

In addition, in a laser image forming apparatus using RGB light emitting elements, there is a proposal to use a single modulation element in a time-division manner using an RGB light emitting element array (for example, Patent Document 2).
Japanese Patent Laid-Open No. 10-293268 Japanese Patent Laid-Open No. 2001-249400

  To date, there have been proposals for reducing speckle noise in laser displays, but there are few proposals for reducing speckle noise in the wavelength range with high visibility, which has the greatest effect on the viewer.

  An object of the present invention is to reduce speckle noise in a wavelength range with high visibility in a laser image forming apparatus using a laser light source, and to provide a vivid image that cannot be expressed by a conventional display.

  In order to solve the above problems, a laser image forming apparatus according to claim 1 of the present invention is a laser image forming apparatus having a laser light source and a two-dimensional modulation element for performing image modulation, wherein the center wavelength is 430 to 475 nm. B, G and Y of 480 to 560 nm, and R of 610 to 680 nm, a four-color BGYR laser light source, and at least one of the G and Y laser light sources is a wavelength conversion laser, The difference between the center wavelengths of the G and Y laser light sources is 2 nm or more and 60 nm or less.

  The laser image forming apparatus according to claim 2 of the present invention is the laser image forming apparatus according to claim 1, wherein the center wavelengths of G and Y are G: 480 to 480 of the four-color BGYR laser light sources. 520 nm, Y: 520 to 560 nm.

  A laser image forming apparatus according to claim 3 of the present invention is a laser image forming apparatus having a laser light source and a two-dimensional modulation element that performs image modulation. B, 480 to 480 having a center wavelength of 430 to 475 nm. When a pixel having a color gamut that can be displayed by using both G and Y is displayed, a G and Y laser beam source of G and Y of 560 nm and R of 610 to 680 nm is displayed. And Y output from the laser light sources.

  According to a nineteenth aspect of the present invention, in the laser image forming apparatus according to the third aspect, when displaying pixels in a color gamut that can be displayed using both G and Y, In this case, the luminance displayed for G and Y is a luminance value of 2/3 to 3/2 with respect to one.

  A laser image forming apparatus according to a fourth aspect of the present invention is the laser image forming apparatus according to the first aspect, wherein the input image signal input to the image forming apparatus is controlled to output four or more color signals. The output image control signal is converted into an output image control signal.

  According to a fifth aspect of the present invention, in the laser image forming apparatus according to the first aspect, the modulation of the laser light outputted from the laser light sources of four or more colors is controlled independently for each color. It is characterized by.

  A laser image forming apparatus according to a sixth aspect of the present invention is the laser image forming apparatus according to the fifth aspect, wherein each color has a color corresponding to an input image signal input to the image forming apparatus and / or a viewing environment. The output power modulation of the laser light source is controlled independently.

  A laser image forming apparatus according to claim 7 of the present invention is the laser image forming apparatus according to claim 1 or 5, wherein the laser image forming apparatus has one two-dimensional modulation element, and the two The two-dimensional modulation element is time-divided and used for the laser light from each of the four or more color laser light sources.

  A laser image forming apparatus according to an eighth aspect of the present invention is the laser image forming apparatus according to the seventh aspect, wherein each division time of the image modulation of the two-dimensional modulation element is modulated in accordance with an input image signal. It is characterized by.

  A laser image forming apparatus according to claim 9 of the present invention is the laser image forming apparatus according to claim 7, wherein each division time of image modulation of the two-dimensional modulation element is determined by using laser light emitted from a laser light source. It modulates according to the output of the laser light source monitor to monitor and / or the display mode to set.

  A laser image forming apparatus according to claim 10 of the present invention is the laser image forming apparatus according to claim 5 or 7, wherein the output image control controls the output of each color signal of four or more colors converted from the input image signal. The signal includes at least a modulation signal of a two-dimensional modulation element and a modulation signal of laser light intensity.

  A laser image forming apparatus according to an eleventh aspect of the present invention is the laser image forming apparatus according to the fifth or seventh aspect, wherein the output image control controls the output of each color signal of four or more colors converted from the input image signal. The signal includes at least a modulation signal of a two-dimensional modulation element and a modulation signal of a laser beam emission time.

  A laser image forming apparatus according to a twelfth aspect of the present invention is the laser image forming apparatus according to the eleventh aspect, wherein the laser beam emission time is determined by the image modulation of the two-dimensional modulation element according to the input image signal. Each of the divided times is modulated and synchronized.

  A laser image forming apparatus according to a thirteenth aspect of the present invention is a laser image forming apparatus having a laser light source and a two-dimensional modulation element that performs image modulation. The laser light sources of four or more colors have a time for the laser light sources of a plurality of colors to emit laser light to the two-dimensional modulation element at the same time.

  A laser image forming apparatus according to a fourteenth aspect of the present invention is the laser image forming apparatus according to the thirteenth aspect, wherein each of the laser light sources of the plurality of colors has another laser light source with respect to the two-dimensional modulation element. The emission power modulation during the time of simultaneous emission and the emission power modulation during the time when the laser light source emits only a single color to the two-dimensional modulation element are controlled independently. Is.

  According to a fifteenth aspect of the present invention, in the laser image forming apparatus according to the first aspect, the color display range in the chromaticity coordinates is controlled in accordance with the viewing environment. .

  According to a sixteenth aspect of the present invention, in the laser image forming apparatus according to the fifteenth aspect, the color display range is wider than the input image signal reference chromaticity range and the input image signal reference color. It is a range according to the degree or a range according to the color reproducible range.

  A laser image forming apparatus according to claim 17 of the present invention is characterized in that, in the laser image forming apparatus according to claim 6 or 14, the laser cooling temperature is controlled in accordance with the emission power modulation of the laser light source. Is.

  A color image forming method according to claim 18 of the present invention is a color image forming method for forming an image using four or more colors of laser light sources and one or a plurality of two-dimensional modulation elements for performing image modulation. In accordance with an input image signal, the image modulation by the one or more two-dimensional image modulation elements and the laser light output modulation of the laser light sources of four or more colors are synchronized to form an image. To do.

  According to the laser image forming apparatus and the color image forming method of the present invention, in the laser image forming apparatus using the laser light source, there is an effect that an image having no noise and large contrast can be displayed.

  That is, according to the laser image forming apparatus of the present invention, since four color laser light sources having different center wavelengths are used, there is no speckle noise and a vivid image that cannot be expressed by a conventional display is displayed. There is an effect that can.

  Further, according to the laser image forming apparatus of the present invention, the four color laser light sources are set to BGYR, and the difference between the center wavelengths of the G and Y laser light sources is set to 2 nm or more and 60 nm or less. There are effects of reducing speckle noise and displaying an image without color unevenness.

  Further, according to the laser image forming apparatus of the present invention, the color reproduction range that can be displayed using both G and Y emits laser light from both the G and Y laser light sources. There is an effect that speckle noise can be reduced by mixing and displaying laser light source colors having high visibility.

  Further, according to the laser image forming apparatus of the present invention, since the laser light output modulation output from the laser light sources of four or more colors is controlled independently for each color, there is an effect that an image with a large contrast can be displayed. is there.

  Further, according to the laser image forming apparatus of the present invention, each division time of the image modulation of the two-dimensional modulation element is modulated according to the output of the laser monitor and / or the display mode to be set. There is an effect that compensation can be made when the brightness or color changes.

  Further, according to the laser image forming apparatus of the present invention, the laser light emission time is synchronously modulated with the modulation of each division time of the image modulation of the two-dimensional modulation element in accordance with the input image signal. The number of gradations and contrast can be increased, and there is an effect that various video expressions are possible.

  In addition, according to the laser image forming apparatus of the present invention, each of the laser light sources of a plurality of colors has its emission power modulation and two-dimensional modulation during the time when another laser light source emits simultaneously to the two-dimensional modulation element. Since the output power modulation during the time when the laser light source emits only a single color to the element is controlled independently, the color temperature is kept unchanged while keeping the power when emitting in a single color. There is an effect that can be adjusted.

  In addition, according to the laser image forming apparatus of the present invention, the color display range in the chromaticity coordinates is controlled according to the viewing environment, so that it is possible to suppress a decrease in contrast due to a change in the viewing environment.

Embodiments of the present invention will be described below with reference to the drawings.
(Embodiment 1)
FIG. 1 is a schematic diagram of a laser image forming apparatus 100 according to Embodiment 1 of the present invention. FIG. 1 shows a projection display (laser display) using a plurality of laser light sources and a single modulation element.

  In FIG. 1, a laser image forming apparatus 100 according to the first embodiment includes four (4) laser light sources (101B, 101G, 101Y) of blue (B), green (G), yellow-green (Y), and red (R). , 101R), a modulation element 107 that modulates an image, an illumination optical system 102 that illuminates the modulation element 107, and a projection optical system 108 that projects a two-dimensional image on the screen 10. The light emitted from the laser light sources (101B, 101G, 101Y, 101R) of each color is guided to the illumination optical system 102 that illuminates the modulation element 107. The illumination optical system 102 includes speckle noise removing means 103, an optical integrator 104, and a projection optical system 106. The light of the laser light source is shaped into the same shape as the effective surface of the modulation element 107, and the light intensity distribution is made substantially uniform. Then, the modulation element 107 is illuminated. In the first embodiment, one modulation element 107 and one light integrator 104 are used for four colors of light, and after the four colors are combined by the dichroic mirror 121, the combined light is combined with the light integrator 104 and the modulation element. Guided to 107. In order to combine the four colors, the polarization directions of the laser beams can be changed and combined using a polarizing prism or the like. Further, it is only necessary to design the optical path so that the laser beams of the respective colors can enter the optical integrator 104 without being multiplexed.

  The four colors of laser light are sequentially emitted, and one modulation element 107 is time-divided and used, and a color image is displayed by time-average additive color mixing on the screen. The sequential emission of laser light may always be emitted one color at a time, or may be combined with the time during which laser light is emitted simultaneously from a plurality of color laser light sources.

  The modulation element 107 according to Embodiment 1 is a two-dimensional modulation element, and an element having a switching frequency of several hundred Hz or more is used. Specifically, a reflection type two-dimensional modulation element composed of a digital micromirror device (DMD) is used. The two-dimensional image is enlarged and projected on the screen 10 by the projection optical system 108, and the viewer can see a vivid image.

  As described above, in the laser image forming apparatus according to the first embodiment, one modulation element 107 is time-divided and used, but the laser image forming apparatus uses a plurality of modulation elements corresponding to each color. On the other hand, when one modulation element is used in a time-sharing manner with RGYB four-color laser light sources, the laser emission time of each laser light source is short, so that the output peak power of the laser light source is four times necessary to obtain the same white luminance. It becomes. In order to obtain a high emission peak power of a laser light source, it is necessary to increase the number of laser light sources in each color and the emission peak power per laser light source, which causes problems in cost and reliability. In the present invention, it is possible to suppress the emission peak power by having time to emit laser beams simultaneously from the laser light sources of a plurality of colors. For example, while RGYB alone emits to obtain white luminance, peak power for obtaining the same white luminance can be suppressed to 75%, light source cost can be reduced, and reliability can be obtained.

  In the case of using a plurality of colors at the same time, a light source such as a lamp or LED has a problem that although brightness is ensured, color contrast is lowered due to additive color mixing, and sufficient color reproduction cannot be performed. In particular, it becomes impossible to reproduce a color having high brightness near the apex of the RGB triangle in the color reproduction range indicated by the chromaticity coordinates. However, in the present invention, by using a monochromatic laser light source, it is possible to brightly display RGYB colors with high saturation and to secure a sufficient color reproduction range. Since the laser light source is monochromatic, the color purity is extremely high, and it is possible to display a color with higher saturation than conventional displays. When the laser light source is used, the colors in the image signal range and the range that is often seen in daily life are mixed colors of the laser light source colors (inside the RGB triangle). It is possible to reproduce the color sufficiently while using it.

  The laser image forming apparatus of the present invention has a modulation element that performs image modulation, and has laser light sources of four or more colors having different center wavelengths. Speckle noise due to laser light interference causes fine fluctuations in the light intensity distribution to the viewer, but the speckle pattern generated from laser light with different center wavelengths is different, and if the viewer perceives different patterns simultaneously, Fluctuation averaging occurs, and the amount of fluctuation with respect to the total light intensity is reduced. Even if the perception of different patterns is not exactly the same in time, if different patterns reach the viewer within a time period that the viewer cannot distinguish, the patterns are perceived as overlapping, reducing the amount of fluctuation (speckle noise) Will be. A general laser image forming apparatus is composed of three colors of RGB. However, since four colors are used in the present invention, the number of patterns increases and speckle noise is reduced.

  The center wavelength of the laser light source of the present invention is four colors BGYR of blue (B) of 430 to 475 nm, green (G) and yellow green (Y) of 480 to 560 nm, and red (R) of 610 to 680 nm. It is preferable to have at least the laser light source.

  In the laser image forming apparatus according to the first embodiment, it is preferable to have the color display range size and brightness, which are the characteristics of the laser image forming apparatus. For this reason, the center wavelength of the blue (B) laser light is preferably 430 to 475 nm with high visibility and a small CIE chromaticity coordinate y value, and the center wavelength of the red (R) laser light has high visibility and color. 610-680 nm with a large degree coordinate x value is preferable. The central wavelengths of the green (G) laser and the yellow-green (Y) laser light have high visibility, and by increasing any y value and decreasing any x value on the chromaticity coordinates, brightness and color The size of the display range can be obtained. For this reason, it is preferable that the center wavelengths of G and Y are 480 to 560 nm. By using four colors of laser light, the color display range on the chromaticity diagram is expanded from a triangle in the case of three colors to a quadrangle, increasing the degree of color freedom and enabling vivid display.

  In the first embodiment, a semiconductor laser having a central wavelength of 455 nm is used for B, a wavelength conversion laser having a central wavelength of 490 nm is used for G, a wavelength conversion laser having a central wavelength of 540 nm is used for Y, and a semiconductor laser having a central wavelength of 635 nm is used for R. A CIE chromaticity diagram showing the color display range (thick solid line) of the first embodiment at this time is shown in FIG. FIG. 2A also shows an sRGB standard range (thin solid line) that is a displayable range on a conventional CRT for comparison. In Embodiment 1, it can be seen that a very wide range of color reproduction is possible. When displaying a color according to the image signal, it is only necessary to display the color reproduction range of the sRGB standard. In the first embodiment, since the color reproduction range of sRGB is inside the RGYB square or ΔBYR (dashed line) as shown in FIG. 2B, the RGYB four colors or the BYR three colors of the laser light source are always mixed. The color will be displayed. As a result, due to the monochromaticity of the laser and the wide color display range, color reproduction can be achieved even when a mixed color in which a plurality of colors of laser beams are simultaneously emitted is used in combination. In order to secure a sufficient color reproduction range, it is preferable that the time for emitting a plurality of colors simultaneously is not longer than the time for monochromatic emission even when a laser light source is used.

  Further, since the laser light source exhibits monochromaticity, when displaying a single color (the color of the vertex of the RGYB quadrangle), the color saturation is extremely high, and the image observer feels relatively bright. In order to compensate for this, it is necessary to display colors near the vertices of the RGYB square with relatively low brightness. In the first embodiment, by having time to simultaneously emit laser beams of a plurality of colors, the brightness of a single color can be suppressed, and a balanced color display can be achieved.

  Speckle noise is perceived strongly at a wavelength with high visibility because it causes brightness fluctuations in which light intensity fluctuations are perceived. For this reason, it is preferable that the G and Y laser beams have a wavelength range with high visibility of 480 to 560 nm, and the effect of reducing speckle noise is particularly greater than when two colors are used in other wavelength ranges. Further, when the center wavelengths of the G and Y laser beams are two colors outside the range of 480 to 560 nm, the laser beam having a wavelength shorter than 480 nm is perceived as blue, and if the wavelength is longer than 560 nm, the laser beam is yellow. Perceived. Since the two colors at this time have opposite hues, the speckle noise is recognized as color unevenness in addition to brightness fluctuation. For this reason, even if the speckle pattern is different and the brightness fluctuation is reduced, if it is recognized as color unevenness, the noise reduction effect is lost. For this reason, the center wavelengths of G and Y are preferably in the range of 480 to 560 nm.

  In order to obtain an effect of reducing speckle noise, it is preferable that the center wavelength is different by 2 nm or more so that the correlation between the G and Y speckle patterns is eliminated. In addition, if the difference between the center wavelengths of G and Y is large, it is perceived as color unevenness even if the hue is not opposite. If the difference between the center wavelengths is 60 nm or less within the range of 480 to 560 nm, these speckle patterns are in a substantially mixed color state in which grains near the resolution of the human eye are mixed, and thus are not recognized as color unevenness.

  In the image forming apparatus 100 according to the first embodiment, it is preferable that at least one of the G and Y laser light sources is a wavelength conversion laser. The wavelength conversion laser is a laser that performs wavelength conversion of the fundamental laser beam. Wavelength conversion includes a double wave whose wavelength is 1/2, a triple wave whose wavelength is 1/3, and a sum frequency and a difference frequency using two fundamental waves. As the fundamental wave laser beam, a solid laser, a gas laser, a fiber laser, or a semiconductor laser can be used, and the wavelength conversion laser can be designed with a very wide range of wavelengths. For the G and Y laser beams, it is preferable to use a wavelength conversion laser capable of freely selecting a wavelength for the design of color and brightness. In addition, as the laser light sources of other colors, general light sources using laser oscillation can be used, and semiconductor lasers, gas lasers, fiber lasers, solid lasers, and the like can be used.

  Moreover, as for the center wavelength of green (G) and yellowish green (Y), it is preferable that G is 480-520 nm and Y is 520-560 nm. Since the color range perceived by a person is within the horseshoe shape (broken line) indicated by the monochromatic light source spectrum on the chromaticity diagram of FIG. 2A, when four colors are selected, the color becomes a quadrangle that occupies as much of the horseshoe shape as possible. The display range is required. Therefore, by setting the center wavelength of G to 480 to 520 nm and the center wavelength of Y to 520 to 560 nm, it is possible to obtain a wide color display range using the monochromaticity of the laser light and four colors. It can deliver a colorful image that is not available.

  In a laser image forming apparatus using four or more colors of laser light having different wavelengths, an input image signal input to the laser image forming apparatus is converted into an output image control signal for controlling the output of the number of colors of the laser light, and output image control is performed. It is preferable to control each color according to the signal. Specifically, even if the input image signal corresponds to three colors, the input image signal is extended and converted into output image control signals corresponding to four or more color signals. By modulating each color with gradation, the color display range can be expanded and controlled rather than the control with three colors, and a vivid image can be created. In the laser image forming apparatus according to the first embodiment, when converting an input image signal having a high luminance and mixed color into an output image control signal, it is preferable to convert the laser light source color having a high visibility so as to be mixed. . Specifically, in the first embodiment, when displaying White, it is possible to display using only three colors of BGR or BYR, but the display is converted to display using all of BGYR. That is, even when the same color is displayed, the number of speckle patterns generated on the screen can be increased and speckle noise can be reduced by mixing laser light source colors having high visibility. More preferably, when converting into an output image control signal, the laser light source colors having high visibility are set to have the same brightness as much as possible. For example, when displaying White, conversion is performed so that the luminances of G and Y are substantially the same on the screen.

  In the first embodiment, as shown in FIG. 2B, the color within the range of sRGB (thin solid line) is included in ΔBYR (dashed line), and it is within the range of sRGB without outputting G. The color can be displayed. Here, as shown in FIG. 2A, the thick solid line of the square is the color display range of the first embodiment. However, in the present invention, in order to reduce speckle noise, even when only three colors of BYR can be displayed, G is added and the output of the video signal is converted into four colors so that the four colors are displayed. Similarly to this, when display is possible only with three colors of BGR, Y is added to display with four colors. In this way, G is displayed when Y is displayed and Y is displayed simultaneously when G is displayed, so that laser light source colors with high visibility are mixed and displayed, thereby reducing speckle noise. be able to. In this way, it is preferable that the color reproduction range that can be displayed using both G and Y displays both G and Y outputs. In particular, in a bright image (display such as White), it is preferable that the luminance component of each color of the pixel displayed on the screen is converted into a display signal of four colors so that G and Y are substantially the same.

  When G and Y are displayed with substantially the same luminance, the speckle noise reduction effect is greatest. Here, the substantially same luminance is a luminance value of 2/3 to 3/2 for one side. A pixel signal of a bright image is when the luminance value of the input signal is 0.8 times or more that of the input signal that provides the maximum luminance.

  In a laser image forming apparatus using a laser light source, a method of scanning a laser beam pixel by pixel on a screen has been proposed. In the present invention, an image modulated by a two-dimensional or one-dimensional modulation element is projected on a screen. To do. When scanning laser light pixel by pixel, the power density increases because a convergent beam is used, and control becomes very difficult when a high output (bright) image is formed. On the other hand, when a two-dimensional or one-dimensionally spread beam is used on the modulation element, a high-power laser beam can be easily used, and a bright image can be delivered to the viewer. In particular, when a two-dimensional modulation element is used, the power density can be lowered as compared with one dimension, and control becomes easier. As the two-dimensional modulation element, an element using a two-dimensional array micromirror, a two-dimensional array liquid crystal element, or the like can be used.

FIG. 3 is a flowchart showing a color image forming method of the laser image forming apparatus according to the first embodiment.
First, the input image signal is converted into an output image control signal for controlling the output of each color signal of four colors (BGYR). Then, in accordance with the output image control signal, the two-dimensional modulation element is modulated and the modulation of the laser beam emission output is controlled independently for each of the B, G, Y, and R colors. In the laser image forming apparatus according to the first embodiment, one two-dimensional modulation element is used for four-color laser light sources, and the laser light emission timing of each color and the image modulation timing of each color in the two-dimensional modulation element are determined. Control is performed in synchronization, and laser beams of different colors are sequentially emitted from the laser light sources, and the two-dimensional modulation element sequentially modulates the images of the respective colors to form a color image.

  In the laser image forming apparatus of the first embodiment, the emitted light intensity of the laser light is changed independently for each color for each frame by the image signal. The output image can represent a gradation image obtained by multiplying the intensity of the laser beam and the modulation by the modulation element. For example, if the modulation element controls 256 gradations and the laser light intensity is controlled by 16 gradations from the minimum value to the maximum value, one frame can express 256 gradations of 4 colors, and the sequence includes 4 colors 256 × 16 (4096) gradation image representation is possible. If the laser light intensity control width (maximum value / minimum value) is 1000 and the contrast performance of the modulation element is 1000: 1, the contrast of the sequence is 1000000: 1, and rich image expression is possible.

  The laser image forming apparatus of the present invention has a two-dimensional modulation element, and controls the light output modulation of the laser light source independently for each color. By performing image modulation with a two-dimensional modulation element and controlling each color independently, the color expression of the sequence can be enriched as described above, and the laser light emission intensity control width of each color is widened. An image with very high contrast can be obtained. In addition, the light output control of the laser light source can be adjusted according to the viewing environment or the like for color adjustment of the entire image, and the light output gradation can be given by an image signal. In the present invention, laser light output modulation for each color is controlled independently, and image modulation is performed by a two-dimensional modulation element, whereby finer adjustments can be made and an image with a wide contrast can be provided. Since the laser image forming apparatus of the present invention uses a laser light source, high-speed and linear output control can be performed by current-voltage control to the light source, and as a video, high-speed modulation for each frame and a wide dynamic range are possible. Can control.

  Further, in the laser image forming apparatus of the present invention, by controlling the emission power modulation of the laser light source independently for each color, the laser light output of each laser light source can be suppressed and output according to the image, and the light output is related. It is possible to save power. In addition, the laser light source can be used with a long life by suppressing the laser light output. Further, by performing image modulation in synchronization with the modulation element, the number of gradations and contrast of the image can be increased, and various video expressions can be made possible.

  In the first embodiment, it is preferable that the independent control of the laser light source emission power modulation is performed according to the input image signal and / or viewing environment. By modulating the emission power of the laser light source in accordance with the input image signal, the number of gradations and contrast can be increased and power can be saved as described above. Since a laser light source is used in the present invention, high-frequency power modulation is possible, and power modulation can be performed for each frame and within one frame, which was not possible with a lamp type or the like.

  In addition, by changing the emission power independently for each color according to the viewing environment, even if the viewing environment changes, the color change can be compensated for display. In the present invention, in addition to the brightness of a single color, a mixed color at the time of simultaneous emission of a plurality of colors can be controlled, so that even if the viewing environment changes, the color change can be widely compensated. It should be noted that, in the case where the viewing environment is dark or the like, even when the brightness to be displayed is suppressed, it is possible to control the color change compensation while also saving power by suppressing the output power.

  Further, in the first embodiment, each of the four color laser light sources has one optical integrator and a two-dimensional modulation element, and sequentially emits laser light to use the two-dimensional modulation element in a time-sharing manner. Image modulation is performed. When using laser light sources of a plurality of colors, if an optical component and a modulation element are prepared for each color, the size and cost are increased. In the present invention, it is preferable to sequentially emit laser beams to laser light sources of a plurality of colors and use only one optical integrator and a two-dimensional modulation element, respectively. The system can be reduced in size and cost.

  In the laser image forming apparatus of the first embodiment, the output image control signal converted from the input image signal input to the laser image forming apparatus includes a signal for modulating the two-dimensional modulation element of each color, And a signal for modulating the laser light intensity of each color. According to such a configuration, it is possible to perform modulation in which two-dimensional modulation element modulation and laser light intensity modulation are combined, and an output image having rich color expression and large contrast can be obtained.

  The color image forming method of the first embodiment is characterized in that image formation is performed by synchronizing image modulation by a two-dimensional modulation element and four-color laser light output modulation in accordance with an input image signal. . By adopting such a method, it is possible to obtain a color image having a wide color display range, vivid and high contrast.

  The laser image forming apparatus of the present invention preferably includes speckle noise removing means in addition to using a four-color laser light source. By providing the speckle removing means, speckle noise that reaches the viewer can be removed more efficiently. In the first embodiment, an element (specifically, a rotating lenticular lens) that changes the deflection angle of the beam with time is provided. As the speckle noise removing means, means for changing the deflection angle for illuminating the two-dimensional modulation element with time or means for widening the spectrum width and light source area of the laser light may be used.

  As described above, the laser image forming apparatus according to Embodiment 1 of the present invention is a laser image forming apparatus having a laser light source and a two-dimensional modulation element that performs image modulation, in which red (R), green (G), Four color laser light sources (101R, 101G, 101Y, 101B) having different center wavelengths of yellow green (Y) and blue (B) are used, and in particular, lasers of G and Y which are laser light source colors having high visual sensitivity. Since light can be emitted and displayed at the same time, speckle noise in a wavelength region with high visibility can be reduced.

  In addition, since the difference between the central wavelengths of the G and Y laser light sources (101G, 101Y) is set to 2 nm or more and 60 nm or less, speckle noise in a wavelength range with high visibility is reduced and an image without color unevenness is displayed. can do.

  In addition, the color reproduction range that can be displayed using both G and Y reduces speckle noise in a wavelength range with high visibility by displaying both G and Y outputs. be able to.

  Further, since the light output modulation of the laser light source is controlled independently for each color, finer adjustments can be made according to the image, and an image with a wide contrast can be provided.

  In addition, since the image modulation by the single two-dimensional modulation element 107 and the four-color laser light output modulation are synchronized in accordance with the input image signal, the image formation is performed. It can be increased, and various video expressions can be made possible.

(Embodiment 2)
The laser image forming apparatus according to Embodiment 2 of the present invention uses the division time, which is the modulation time for each color of the two-dimensional modulation element, when performing image modulation from each laser light source in the laser image forming apparatus of Embodiment 1. It is to be modulated.

  FIG. 4 is a flowchart of the color image forming method of the laser image forming apparatus according to the second embodiment. Since the configuration of the laser image forming apparatus according to the second embodiment is the same as that of the laser image forming apparatus 100 according to the first embodiment, the description thereof is omitted.

  In the laser image forming apparatus according to Embodiment 2, the division time for the modulation operation of each color of the two-dimensional modulation element is modulated in accordance with an input image signal input to the laser image forming apparatus. Specifically, for example, assuming that 1 frame is 1/60 sec, each division time of blue (B), green (G), yellow green (Y), and red (R) is (B, G , Y, R) (unit: sec) is (1/240, 1/240, 1/240, 1/240), and in another frame B (1/480, 1/480, 1/240, 1 / 120). At the same time, in the laser light output modulation, the laser light emission time is modulated so as to be within each division time of the image modulation of the two-dimensional modulation element, and the laser light intensity is also modulated independently for each color.

  In the laser image forming apparatus according to the second embodiment, it is preferable to modulate the division time of the two-dimensional modulation element into the laser light sources of the respective colors according to the input image signal. By modulating the division time, the number of gradations of each color can be changed for each frame, and only the number of gradations of necessary colors can be increased. For example, in a sunset scene, the red (R) division time can be increased, the number of red gradations can be increased, and the red expression can be made finer.

  The output image control signal converted from the input image signal preferably includes a signal for modulating the laser beam emission time together with a signal for modulating the two-dimensional modulation element, as in the first embodiment. By performing laser beam emission time modulation, laser beam output modulation can be performed even at a constant intensity. More preferably, the laser beam emission time is synchronously modulated with each division time of the image modulation of the two-dimensional modulation element. According to such a configuration, it is possible to use each division time for image modulation of the two-dimensional modulation element without waste.

FIG. 5 shows another example of the laser emission pattern configuration of the laser image forming apparatus according to the second embodiment.
For example, when the input image signal is a dark scene, each color is sequentially emitted as shown in FIG. 5A and a period k in which the output of all colors is lowered is provided. When the input image signal is a bright scene, As shown in FIG. 5B, a plurality of colors (four colors in the figure) are emitted simultaneously, and a period w for emitting a mixed color pattern is provided. During a period in which a mixed color W (White) pattern is emitted, the modulation element also modulates an image according to W. At this time, the input image signal is converted into five colors corresponding to R, G, Y, B, and W to form an image of each color. The display pattern of the period w in which a plurality of colors are emitted converts the signal so as to correspond to the brightness of the pixel.

  In the second embodiment, as in the first embodiment, it is preferable to emit at least two colors G and Y at the same time during a period in which a plurality of colors are emitted. Outputs of two colors G and Y in a multi-color emission period can be reliably applied to a pixel displaying a bright image signal, and a pixel displaying a bright image signal with remarkable speckle noise can be efficiently converted to G. And Y and Y output are combined to reduce speckle noise.

  Further, in the second embodiment, it is preferable that the combination of R and G and Y and B that are close to the opposite hue is emitted continuously, and thereby the color blur due to the sequential emission is reduced. Further, as shown in FIG. 6, it is preferable that G and Y are emitted continuously because a reduction effect of speckle noise is easily obtained. Specifically, it is preferable that R → G → Y → B →... Or B → Y → G → R →... As shown in FIG. Moreover, you may provide the period which cuts off multi-color emission or an output between the said emission orders.

  Further, in the second embodiment, the modulation element and the laser light source perform modulation in synchronization with the mixed color that emits a plurality of colors at the same time. By controlling the output power modulation when the light is emitted simultaneously at the same time, the output power ratio (mixing ratio) simultaneously emitted can be controlled while performing monochromatic power modulation. it can.

  FIG. 6 is a diagram showing the laser beam emission timing in the case where the emission power modulation during the time when a plurality of colors are emitted simultaneously and the emission power modulation when only a single color is emitted are controlled independently. In this example, the temperature is adjusted by White that emits four colors simultaneously.

  In FIG. 6, an image in which the ratio of Red is reduced and the color temperature is increased is shown. In the present invention, by changing the mixing ratio of the power for emitting a plurality of colors at the same time, it is possible to cope with changes such as the color temperature depending on the viewing environment and the viewer's preference. In the example of FIG. 6, the color temperature can be adjusted while changing the output power ratio of the four colors at the same time, while maintaining the power when the RGYB single color is emitted. In the second embodiment, the example in which the emission power ratio is changed when displaying White has been described. Similarly, when a plurality of colors other than White are emitted, power mixing is performed depending on the viewing environment and the preference of the viewer. The ratio can be controlled.

  As described above, the laser image forming apparatus according to the second embodiment of the present invention is a laser image forming apparatus having one optical integrator and a two-dimensional modulation element. Thus, it is used for a laser light source of a plurality of colors, and each division time of the time-division two-dimensional modulation element is modulated in accordance with the input image signal. The number can be changed and only the number of gradations of necessary colors can be expanded.

  In addition, pixels that display bright image signals such as White are displayed using four-color laser light sources including G and Y, so that pixels that display bright image signals with remarkable speckle noise are efficiently displayed. It is possible to reduce the speckle noise by using a combination of G and Y.

  In addition, since the output power modulation during the time when multiple colors are emitted simultaneously and the output power modulation during the time when only a single color is emitted are controlled independently, it is the same when emitting in a single color. The color temperature can be adjusted.

(Embodiment 3)
The laser image forming apparatus according to Embodiment 3 of the present invention uses four color laser light sources in a laser image forming apparatus that uses three optical integrators and two-dimensional modulation elements.

  FIG. 7 is a schematic diagram of a laser image forming apparatus 200 according to Embodiment 3 of the present invention. In FIG. 7, the same components as those in FIG.

  The laser image forming apparatus 200 according to Embodiment 3 includes three optical integrators 1041 to 1043, two-dimensional modulation elements 1071 to 1073, and four color laser light sources (101R, 101G, 101Y, and 101B). In the third embodiment, the green laser light source 101G and the yellow-green laser light source 101Y form a set and share one set of the optical integrator 1042 and the two-dimensional modulation element 1072. The two-dimensional image modulation elements 1071 to 1073 are transmissive two-dimensional modulation elements, and specifically have a configuration in which a liquid crystal element array and a polarizer are combined. Blue (B) and red (R) each have a pair of light integrators 1041 and 1043 and two-dimensional modulation elements 1071 and 1073, and the four colors of laser light are integrated and additively mixed on the screen, Vivid images can be seen.

  The illumination optical system 102 includes speckle removing means 1031 to 1033, optical integrators 1041 to 1043, and projection optical systems 1061 to 1063, and shapes and uniforms the light of the laser light source to illuminate the two-dimensional modulation elements 1071 to 1073. In the third embodiment, the light from the three two-dimensional modulation elements 1071 to 1073 is combined by the dichroic prism 109, and the combined light causes the projection optical system 108 to enlarge and project a color image on the screen 10.

  In the third embodiment, a semiconductor laser with a central wavelength of 455 nm is used as 101B, a wavelength conversion laser with a central wavelength of 515 nm is used as 101G, a wavelength conversion laser with 532 nm is used as 101Y, and a semiconductor laser with a central wavelength of 635 nm is used as 101R. The color display range of the third embodiment is shown in FIG. In the third embodiment, like the color display range of the first embodiment (thick solid line shown in FIG. 2 (a)), a range (two-dot chain line) that is much wider than the sRGB standard range (thin solid line). Color display is possible. Similarly to the first embodiment, speckle noise can be reduced by superimposing the G and Y laser light primaries.

  In the third embodiment, the green (G) and yellow-green (Y) image modulations share the two-dimensional modulation element 1072, for example, the following first and second modulations a) and b). Use the method. The input image signal input to the laser image forming apparatus is converted into an output image control signal for controlling the output of each of the four color signals, as in the first embodiment.

  a) First modulation method

  The image modulation pattern of the two-dimensional modulation element is the same pattern for G and Y, and one image modulation pattern is given to the total laser light output of G and Y.

  FIG. 8 shows an example of G and Y laser beam outputs. In FIG. 8, during the period of one image modulation pattern, the total light of G and Y illuminates the modulation element.

  First, FIG. 8A is a diagram showing an example of controlling the output and ratio of G and Y that illuminate one image modulation pattern by the ratio of the laser emission power. In the example of FIG. 8 (a), the G and Y laser emission power ratio and output change for each image modulation pattern, and the output and color for illuminating the modulation element change according to the image signal, display mode, etc. This is a preferable modulation method that enables a wide range of color display, high contrast, and multiple gradations. For bright image signals, the outputs of G and Y are given high, and the modulation element is illuminated so that the luminances of G and Y are substantially the same. By using such a modulation method, the luminance ratio of G and Y to be displayed can be made substantially the same for bright pixels to be displayed, and speckle noise can be reduced.

  FIG. 8B is a diagram showing an example in which the output and ratio of G and Y that illuminate one image modulation pattern are controlled by the pulse time width of laser light emission. In the example of FIG. 8B, in the case of a bright image signal, in order to increase the average output in one image modulation pattern, the emission time ratio of G and Y in one image modulation pattern is increased and one image of G and Y is increased. The laser beam emission power is controlled so that the luminance in the modulation pattern is substantially the same.

  As described above, the first modulation method shown in FIGS. 8A and 8B illuminates one image modulation pattern of the image modulation element with the total output light of G and Y. This is a preferable modulation method capable of displaying with a preferable luminance ratio of G and Y.

  The output image control signals for G and Y include the modulation signal of the same two-dimensional modulation element and the respective laser beam output signals.

  FIGS. 8A and 8B show an example in which the output and ratio of G and Y are changed for each pattern of the modulation element by an input image signal or the like. The output and ratio of Y and Y may be changed, or the output and ratio of G and Y may always be constant. When the output and ratio of G and Y are constant, the G and Y laser light output signals may be the same.

  b) Second modulation method

  The image modulation of the two-dimensional modulation element is time-divided by G and Y as in the first and second embodiments, and two colors are modulated. The G and Y output image control signals include the modulation signals of the respective two-dimensional modulation elements and the laser light output modulation signals, and are synchronized with the timing of image modulation time-divided in the two-dimensional modulation elements. Laser beam is emitted. Laser light output modulation may modulate either the laser light intensity or the emission time, or both. When modulating the laser emission time, each division time of image modulation of the two-dimensional modulation element may be synchronized and modulated. Thereby, a wide range of color display is possible even within a frame, and a more preferable modulation method can be obtained.

  FIG. 9 is a diagram showing an example when the laser beam emission time is modulated while the division timing of the two-dimensional modulation element is kept the same. When the image modulation pattern of the two-dimensional image modulation element is a G-compatible pattern, Y laser light is emitted to illuminate the two-dimensional modulation element. Similarly, when the image modulation pattern is a Y-corresponding pattern, G laser light is emitted to illuminate the two-dimensional modulation element. The example of FIG. 9 is a preferable modulation method that can output G and Y laser beams simultaneously to pixels to be displayed by adding Y and G outputs in the case of either G or Y modulation patterns. Further, in the second modulation method, the laser light output is controlled by changing the emission time of the laser light applied in the modulation pattern of either G or Y according to the input image signal. At this time, in a bright scene, by adding more laser light output, it is possible to compensate for the brightness displayed on the screen to be the maximum brightness, and it is possible to always add G + Y laser light output to bright pixels. Noise can be reduced.

  In the second modulation method, the laser light output applied to any one of the G and Y patterns is changed depending on the input image signal and the display mode, but the laser light output applied to each of these patterns is constant. Also good.

  In the laser image forming apparatus according to the third embodiment, green (G) and yellow green (Y) share the two-dimensional modulation element 1072, but red (R) and blue (B). Controls the modulation of the two-dimensional modulation element and the laser light output modulation independently for each color.

  Similarly to the color image forming method of the first embodiment, the image modulation by the three two-dimensional modulation elements and the four-color laser light output modulation may be synchronized in accordance with the input image signal to perform image formation. Good. By adopting such a method, a color image having a wide color display range, a vivid color and a large contrast can be obtained as in the first embodiment.

  As described above, in the laser image forming apparatus according to Embodiment 3 of the present invention, each of the G and Y laser light sources is shared by using one optical integrator 1042 and two-dimensional modulation element 1072, respectively. Even in a configuration having two modulation elements 1071 to 1073 and optical integrators 1041 to 1043, it becomes possible to use four colors of laser light, and speckle noise with high visibility can be reduced, and the color display range can be reduced. Large and profound visual expression.

(Embodiment 4)
In the laser image forming apparatus according to the fourth embodiment of the present invention, in the laser image forming apparatus according to the second embodiment, the output of the laser light source monitor and / or the display mode is used in order to compensate for changes in image brightness and color. Accordingly, the laser beam emission time and the image modulation division time of the two-dimensional modulation element are controlled.

  FIG. 10A shows an example in which the emission time is controlled in accordance with a signal from the light source monitor of the Red laser light source 101R. The laser light source monitor monitors the laser light output and the emission wavelength. The Red laser light source 101R of the laser image forming apparatus is provided with a power and wavelength monitor (not shown) using a diffraction grating and a two-divided photodetector. In FIG. 10A, it is monitored by the laser light source monitor that the wavelength of the Red laser light source 101R has shifted to the long wavelength side due to a temperature change, and in accordance with this, the emission time is controlled for the initial setting, and the color of the image Compensates for changes in brightness. The change in the visibility and chromaticity coordinates due to the shift of the emission wavelength of the Red laser light source 101R to a long wavelength is compensated by controlling the emission time of R single color and the simultaneous emission time of plural colors. Note that each division time of the image modulation of the two-dimensional modulation element may be modulated so as to be synchronized with the laser light output after the emission time control according to the laser light source monitor.

  FIG. 10B shows an example of the emission time control when the display mode is set so that white luminance is given priority. Depending on the set display mode, it is possible to display white brightness brightly even if the time for simultaneously emitting a plurality of colors is increased and the peak power of the same laser light source is used. In the example of FIG. 10B, the white luminance can be displayed 10% brighter than the initial brightness. Similarly to the control of FIG. 10B, by increasing the simultaneous emission time of a plurality of colors, even with the same white luminance, the peak power of the laser light source is suppressed, and the lifetime reliability of the laser light source is prioritized. Can also be selected. Each division time of the image modulation of the two-dimensional modulation element may be modulated so as to be synchronized with the laser light output after the emission time control according to the display mode to be set.

  Further, when the laser light source monitor detects that the power of any one of the laser light sources of each color is deteriorated, the brightness and color can be compensated by controlling the emission time in the same manner as described above. Similarly, when the power deterioration of the laser light sources of all colors is detected by the laser light source monitor, the brightness can be compensated by increasing the time width for simultaneous emission.

  As described above, in the laser image forming apparatus according to Embodiment 4 of the present invention, the laser light source sequentially emits monochromatic and plural colors according to the laser light source monitor and / or display mode, and two-dimensional modulation. By controlling each division time of the image modulation of the element, it is possible to adjust the brightness and color of the image, and to compensate when the brightness and color of the image change.

  In the present invention, not only a single RGYB color but also a mixed color in which a plurality of colors are emitted simultaneously can be adjusted to make finer adjustments.

  In the fourth embodiment, power and wavelength are detected by a laser light source monitor, and compensation when the wavelength is changed can be adjusted without forcibly increasing the laser output.

  In addition, by controlling the emission time of sequential emission, a viewer can provide an image with favorable image quality.

(Embodiment 5)
In the laser image forming apparatus according to Embodiment 5 of the present invention, in the laser image forming apparatuses of Embodiments 1 to 4, in order to prevent a decrease in color saturation due to a change in viewing environment, a color is changed according to the viewing environment. The display range is controlled.

  A color adjustment method according to the viewing environment of a laser image forming apparatus having RGYB four-color laser light sources and modulation elements will be described using the laser image forming apparatus 100 of the first embodiment. The laser image forming apparatus 100 can display the color inside the RGYB square (thick solid line) as shown in the color displayable range of the CIExy chromaticity diagram of FIG.

  When the sRGB standard input image signal is normally displayed, color display is performed according to the sRGB standard chromaticity. FIG. 11 shows an example of color display at this time.

  In FIG. 11, in the case of sRGB compliant display (thin solid line), display is performed in a range that includes the sRGB color reproduction range (thin broken line) in accordance with the sRGB reference chromaticity and in which the hue and the like do not deviate from the input signal. . In the case of sRGB compliant display, the color saturation may be displayed higher than that of the conventional display within a range in which the hue does not deviate so as to make use of the laser color display possible range.

  The laser image forming apparatus according to the fifth embodiment is characterized in that the color display range in the chromaticity coordinates is controlled according to the viewing environment. That is, when the viewing environment changes and becomes brighter than the normal display, the viewer sees the illumination light. Therefore, when the same image is displayed as before, the color saturation appears to be lowered. In the fifth embodiment, when the viewing environment becomes bright, the color display range is controlled to be larger than normal. That is, when the color saturation appears to be lowered due to illumination light or the like, as shown in FIG. 11, the color display range is set to a range according to the displayable range (thick broken line). For example, when displaying an input image signal of the sRGB standard, the display can be controlled from the sRGB compliant display to the viewing environment compatible display according to the viewing environment. With this control, even when the viewing environment changes and bright illumination light is in the viewer's eyes, a highly saturated color can be displayed. Since the laser image forming apparatus of the present invention has the monochromaticity of the laser light source, it can display a highly saturated color. Even for the same input image signal, a reduction in color contrast can be compensated by displaying a highly saturated color utilizing monochromaticity.

  Note that the change in chromaticity of an image to be displayed can be processed when the input image signal is converted into an output image control signal for controlling the modulation element and the laser light source power. Changes in the viewing environment may be controlled by a viewing environment monitor (not shown) provided on the display surface of the laser image forming apparatus and the like, or may be set by the viewer as needed.

  Further, the laser image forming apparatus of the present invention is preferably accompanied by power control of the laser light source with respect to a change in the color display range depending on the viewing environment. For example, when the illumination light is very bright, it is possible to further suppress a decrease in color contrast by increasing the power of the laser light source more than usual. Even if the illumination light is not white light but colored illumination, the laser image forming apparatus of the present invention has an independent laser light source of RGYB. A decrease in color contrast can be suppressed. When the viewing environment becomes dark, the power of the laser light source can be suppressed, and the power can be saved while keeping the color perceived by the viewer constant.

  As described above, the laser image forming apparatus according to the fifth embodiment of the present invention is sRGB compliant with the normal display in the color display range when the viewing environment changes and becomes brighter and the color saturation appears to decrease. By controlling the display to display corresponding to the viewing environment, it is possible to prevent a decrease in color saturation due to a change in the viewing environment.

  Although the laser image forming apparatus 100 according to the first embodiment has been described as an example in the fifth embodiment, the color display range is similarly controlled in the laser image forming apparatus 200 according to the third embodiment according to the viewing environment. Needless to say, you can.

  In the laser image forming apparatuses according to Embodiments 1 to 5 of the present invention, it is preferable to simultaneously control the laser cooling temperature when the emission power of the laser light source is modulated by the input image signal or the viewing environment. In particular, when the laser light source power is continuously emitted at a high power, the cooling temperature is controlled to be lowered. By controlling the cooling temperature in accordance with the emission power modulation control of the laser light source, high reliability of the laser light source can be ensured and laser light can be output with high efficiency. Further, in the case of image display in which the laser light source output is suppressed, the cooling power can be suppressed by further increasing the cooling temperature, thereby further saving power.

  Further, as the laser light source in the laser image forming apparatuses according to Embodiments 1 to 5 of the present invention, a laser light source such as a semiconductor laser, a wavelength conversion laser, a solid laser, or a gas laser can be used. Moreover, you may comprise the laser light source of 1 color from several lasers.

  In addition, since the laser image forming apparatuses according to Embodiments 1 to 5 of the present invention utilize the monochromaticity of the laser light source, for example, including a case where a single color laser light source is composed of a plurality of lasers of the same color, It is preferable to have monochromaticity. Including the case where the laser light source of the same color is composed of a plurality of lasers, the full width at half maximum of each color of the RGYB four-color laser light source is preferably less than 10 nm. By setting the full width at half maximum to less than 10 nm, the advantage of monochromaticity (narrow spectrum width) can be fully utilized with respect to a conventional light source, and the laser image forming apparatus of the present invention can be used. More preferably, the full width at half maximum of the spectrum of the RGYB four-color laser light source is less than 5 nm. If it is less than 5 nm, chromaticity management of each color can be performed more easily.

  In addition, the projection optical system and the screen for projecting the image of the modulation element in the laser image forming apparatuses according to Embodiments 1 to 5 of the present invention are not particularly limited to the embodiment, so long as the viewer can observe the modulation element image. good. The screen may be a reflection type, a front projection type, or a transmission type, a rear projection type. Further, it may be in the form of a liquid crystal display without a projection optical system and having a modulation element as a display surface.

  In the laser image forming apparatuses according to Embodiments 1 to 5 of the present invention, four color laser light sources having different center wavelengths are used. However, the present invention is not particularly limited to this, and five or more colors can be used. .

  Further, in the laser image forming apparatuses according to Embodiments 1 to 5 of the present invention, the four-color laser light sources having different center wavelengths are used, but the two-dimensional spatial modulation elements and / or the respective elements in Embodiments 1 and 2 are used. The modulation control of the laser light source and the fourth and fifth embodiments can be applied to a laser image forming apparatus using three color laser light sources.

  The laser image forming apparatus and the color image forming method of the present invention can be used as an image forming apparatus and method for moving images and still images.

FIG. 1 is a schematic diagram of a laser image forming apparatus according to Embodiment 1 of the present invention. FIG. 2 is a chromaticity diagram showing the color display range according to the embodiment of the present invention. FIG. 3 is a flowchart showing the image forming method according to the first embodiment of the present invention. FIG. 4 is a flowchart showing an image forming method according to the second embodiment of the present invention. FIG. 5 is a diagram showing the laser beam emission timing of the laser image forming apparatus according to Embodiment 2 of the present invention. FIG. 6 shows the laser image forming apparatus according to Embodiment 2 of the present invention, in which the output power modulation during the time when multiple colors are emitted simultaneously and the output power modulation during the time when only one color is emitted are controlled independently. It is a figure showing the laser beam emission timing in the case. FIG. 7 is a schematic diagram of a laser image forming apparatus according to Embodiment 3 of the present invention. FIG. 8 is a diagram showing G and Y laser beam outputs in the laser image forming apparatus according to Embodiment 3 of the present invention. FIG. 9 is a diagram showing an example in which the laser beam emission time is modulated in the laser image forming apparatus according to Embodiment 3 of the present invention. FIG. 10 is a diagram illustrating laser light emission time control in the laser image forming apparatus of the present invention. FIG. 11 is a chromaticity diagram showing a color display range in the laser image forming apparatus of the present invention. FIG. 12 is a schematic view of a conventional laser image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100, 200 Laser image forming apparatus 101B Blue laser light source 101G Green laser light source 101Y Yellow green laser light source 101R Red laser light source 102 Illumination optical system 103, 1031-1033 Speckle noise removal means 104, 1041-1043 Optical integrator 106, 1061-1063 Projection optical system 107, 1071 to 1073 Two-dimensional modulation element 108 Projection optical system 109 Dichroic prism 10 Screen 121 Dichroic mirror 122 Lens 1061a, 1063a Mirror 1061b, 1062, 1063b Field lens 300 Laser image forming apparatus 1R Red laser light source 1G Green laser light source 1B Blue laser light source 2 Illumination optical system 3 Speckle removal means 4 Optical integrator 6 Projection optical system 61 Mirror 62 Field lens 71 Two-dimensional modulation element 8 Projection optical system 9 Dichroic prism 10 Screen

Claims (21)

In a laser image forming apparatus having a laser light source and a two-dimensional modulation element that performs image modulation,
Having four or more laser light sources with different central wavelengths,
A laser image forming apparatus. The laser image forming apparatus according to claim 1.
The center wavelength of the laser light source is
B which is 430 to 475 nm, G and Y which are 480 to 560 nm, and R which is 610 to 680 nm,
Having a four-color BGYR laser light source,
A laser image forming apparatus. The laser image forming apparatus according to claim 2.
At least one of the G and Y laser light sources is a wavelength conversion laser.
A laser image forming apparatus. The laser image forming apparatus according to claim 3.
The difference between the center wavelengths of the G and Y laser light sources is 2 nm or more and 60 nm or less.
A laser image forming apparatus. The laser image forming apparatus according to claim 2.
Among the four-color BGYR laser light sources, the center wavelengths of G and Y are G: 480 to 520 nm, Y: 520 to 560 nm,
A laser image forming apparatus. The laser image forming apparatus according to claim 2.
The color gamut that can be displayed using both G and Y emits laser light from both the G and Y laser light sources.
A laser image forming apparatus. The laser image forming apparatus according to claim 1.
Converting an input image signal input to the image forming apparatus into an output image control signal for controlling the output of each color signal of four or more colors;
A laser image forming apparatus. The laser image forming apparatus according to claim 1.
The modulation of laser light output from the laser light sources of four or more colors is controlled independently for each color;
A laser image forming apparatus. The laser image forming apparatus according to claim 8.
Independently controlling the emission power modulation of the laser light source of each color according to the input image signal and / or viewing environment input to the image forming apparatus,
A laser image forming apparatus. The laser image forming apparatus according to claim 1 or 8,
The laser image forming apparatus comprises:
The two-dimensional modulation element is used as one, and the two-dimensional modulation element is used by dividing the image modulation of the two-dimensional modulation element with respect to each laser beam from each of the four or more color laser light sources.
A laser image forming apparatus. The laser image forming apparatus according to claim 10.
Modulating each division time of image modulation of the two-dimensional modulation element according to an input image signal;
A laser image forming apparatus. The laser image forming apparatus according to claim 10.
Modulating each division time of image modulation of the two-dimensional modulation element according to an output of a laser light source monitor for monitoring laser light emitted from a laser light source and / or a display mode to be set;
A laser image forming apparatus. The laser image forming apparatus according to claim 8 or 10,
The output image control signal for controlling the output of each of the four or more color signals converted from the input image signal includes at least a modulation signal of a two-dimensional modulation element and a modulation signal of laser light intensity.
A laser image forming apparatus. The laser image forming apparatus according to claim 8 or 10,
The output image control signal for controlling the output of each of the four or more color signals converted from the input image signal includes at least a modulation signal of the two-dimensional modulation element and a modulation signal of the laser beam emission time.
A laser image forming apparatus. The laser image forming apparatus according to claim 14.
The laser light emission time is synchronously modulated with the modulation of each division time of the image modulation of the two-dimensional modulation element according to the input image signal.
A laser image forming apparatus. The laser image forming apparatus according to claim 1.
The laser light sources of four or more colors have a time for laser beams of a plurality of colors to emit laser light simultaneously to the two-dimensional modulation element.
A laser image forming apparatus. The laser image forming apparatus according to claim 16.
Each of the laser light sources of the plurality of colors has its emission power modulation during the time when another laser light source emits simultaneously to the two-dimensional modulation element, and the laser light source is only monochromatic with respect to the two-dimensional modulation element. Independent control of the emission power modulation during the time of emitting
A laser image forming apparatus. The laser image forming apparatus according to claim 1.
Control the color display range in chromaticity coordinates according to the viewing environment.
A laser image forming apparatus. The laser image forming apparatus according to claim 18.
The color display range is wider than the input image signal reference chromaticity range and is a range according to the input image signal reference chromaticity or a range according to the color reproducible range.
A laser image forming apparatus. The laser image forming apparatus according to claim 9 or 17,
Along with the emission power modulation of the laser light source, the laser cooling temperature is controlled.
A laser image forming apparatus. A color image forming method for forming an image using laser light sources of four or more colors and one or more two-dimensional modulation elements that perform image modulation,
In accordance with an input image signal, image modulation by the one or more two-dimensional image modulation elements and laser light output modulation of the laser light sources of four or more colors are synchronized to form an image.
And a color image forming method.

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